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Convert repeating decimal to fraction

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5498148
Convert \(0.\overline{7}\) to a fraction in lowest terms. Show the subtraction step used to eliminate the repeating digit.

Hints

- Name the repeating decimal with a variable. - Shift the decimal point by one place so the repeating tails align. - Subtract the aligned equations.

Solution

1. Let \(x=0.\overline{7}\). 2. Then \(10x=7.\overline{7}\). 3. Subtract: \(10x-x=7\), so \(9x=7\). 4. Therefore, \(x=\frac{7}{9}\).

Answer

\(0.\overline{7}=\frac{7}{9}\)
5498158
Convert \(0.\overline{34}\) to a fraction in lowest terms.

Hints

- Count the digits in the repeating block. - Use a power of ten that shifts one complete block. - Check whether the resulting numerator and denominator share a factor.

Solution

1. Let \(x=0.\overline{34}\). 2. Since the period has \(2\) digits, \(100x=34.\overline{34}\). 3. Subtracting gives \(100x-x=34\), so \(99x=34\). 4. Thus, \(x=\frac{34}{99}\), which is already in lowest terms.

Answer

\(0.\overline{34}=\frac{34}{99}\)
5498168
Convert \(0.\overline{052}\) to a fraction in lowest terms. Keep the leading zero as part of the repeating block.

Hints

- Treat every position in the repeating block as significant, including the zero. - Shift by the full length of the period. - Align the repeating tails before subtracting.

Solution

1. Let \(x=0.\overline{052}\). 2. The period has \(3\) digits, so \(1000x=52.\overline{052}\). 3. Subtracting gives \(999x=52\). 4. Therefore, \(x=\frac{52}{999}\), which is in lowest terms.

Answer

\(0.\overline{052}=\frac{52}{999}\)
5498178
Convert \(2.\overline{6}\) to a fraction in lowest terms. Include the whole-number part in your algebraic setup.

Hints

- The repeating tail must line up after shifting. - Subtract the original decimal from the shifted one. - Reduce the resulting improper fraction.

Solution

1. Let \(x=2.\overline{6}\). 2. Then \(10x=26.\overline{6}\). 3. Subtract: \(10x-x=24\), so \(9x=24\). 4. Therefore, \(x=\frac{24}{9}=\frac{8}{3}\).

Answer

\(2.\overline{6}=\frac{8}{3}\)
5498218
Convert \(-0.\overline{18}\) to a fraction in lowest terms.

Hints

- Temporarily work with the positive magnitude. - Shift by the full repeating block. - Apply the sign after reducing the fraction.

Solution

1. First convert the positive decimal. Let \(y=0.\overline{18}\). 2. Then \(100y=18.\overline{18}\), so \(99y=18\). 3. Thus, \(y=\frac{18}{99}=\frac{2}{11}\). 4. Restore the negative sign: \(-0.\overline{18}=-\frac{2}{11}\).

Answer

\(-0.\overline{18}=-\frac{2}{11}\)
5498238
Let \(x=0.\overline{305}\). Which equation should be paired with \(x\) so subtraction removes the repeating tail? A. \(10x=3.\overline{053}\) B. \(100x=30.\overline{530}\) C. \(1000x=305.\overline{305}\) Use the correct equation to convert \(x\) to a fraction.

Hints

- Count all digits in the repeated block. - Choose the shift that returns the same block to the same positions. - Verify that subtraction would cancel every repeating digit.

Solution

1. The period has \(3\) digits, so the correct equation is C: \(1000x=305.\overline{305}\). 2. Subtracting the original equation gives \(999x=305\). 3. Therefore, \(x=\frac{305}{999}\), which is in lowest terms.

Answer

Equation C; \(0.\overline{305}=\frac{305}{999}\)
5498258
The repeating decimal \(0.\overline{54}\) is equal to \(\frac{n}{11}\), where \(n\) is a whole number. Find \(n\) by converting the decimal.

Hints

- Convert the decimal before comparing numerators. - Reduce the fraction to a denominator of \(11\). - Match the reduced form to the given expression.

Solution

1. Let \(x=0.\overline{54}\). 2. Then \(100x=54.\overline{54}\), so \(99x=54\). 3. Thus, \(x=\frac{54}{99}=\frac{6}{11}\). 4. Therefore, \(n=6\).

Answer

\(n=6\)
5498278
Convert \(0.\overline{9}\) to a fraction. Use the result to explain why this decimal equals \(1\), not a number slightly less than \(1\).

Hints

- Apply the same variable method used for any one-digit period. - Subtract the two aligned equations. - Interpret the solved value as an exact equality.

Solution

1. Let \(x=0.\overline{9}\). 2. Then \(10x=9.\overline{9}\). 3. Subtracting gives \(9x=9\). 4. Thus, \(x=1\), so \(0.\overline{9}=1\) exactly.

Answer

\(0.\overline{9}=1\)
5498298
Convert \(0.0\overline{9}\) to a fraction in lowest terms. Explain its relationship to \(0.1\).

Hints

- Shift past the nonrepeating zero. - Use the exact value of a repeating string of nines. - Express the result in both fraction and decimal form.

Solution

1. Let \(x=0.0\overline{9}\). 2. Then \(10x=0.\overline{9}=1\). 3. Therefore, \(x=\frac{1}{10}\). 4. Hence, \(0.0\overline{9}=0.1\) exactly.

Answer

\(0.0\overline{9}=\frac{1}{10}=0.1\)
5498308
A student claims \(0.\overline{81}\) and \(\frac{9}{11}\) are different because one is written as a decimal and the other as a fraction. Convert the decimal and evaluate the claim.

Hints

- Convert the repeating representation before comparing. - Reduce the fraction obtained from the subtraction method. - Different representations can name the same number.

Solution

1. Let \(x=0.\overline{81}\). 2. Then \(100x=81.\overline{81}\), so \(99x=81\). 3. Thus, \(x=\frac{81}{99}=\frac{9}{11}\). 4. The two expressions represent the same rational number.

Answer

The claim is false. \(0.\overline{81}=\frac{9}{11}\).
5498338
Compute \(0.\overline{7}-0.\overline{2}\) exactly. Give the answer as a fraction in lowest terms.

Hints

- Convert both repeating decimals separately. - Notice whether the resulting denominators match. - Perform the exact subtraction after conversion.

Solution

1. Convert \(0.\overline{7}=\frac{7}{9}\). 2. Convert \(0.\overline{2}=\frac{2}{9}\). 3. Subtract: \(\frac{7}{9}-\frac{2}{9}=\frac{5}{9}\).

Answer

\(\frac{5}{9}\)
5498548
Convert \(0.\overline{48}\) to a fraction in lowest terms. Then explain why the denominator changes from \(99\) to \(33\) during reduction.

Hints

- Form the unreduced block-over-nines fraction. - Look for a common factor shared with \(99\). - Explain the denominator change as part of reducing an equivalent fraction.

Solution

1. A two-digit period gives \(0.\overline{48}=\frac{48}{99}\). 2. The numerator and denominator share a factor of \(3\). 3. Dividing both by \(3\) gives \(\frac{48}{99}=\frac{16}{33}\). 4. No further common factor remains.

Answer

\(0.\overline{48}=\frac{16}{33}\). The denominator becomes \(33\) because both \(48\) and \(99\) are divided by \(3\).
5143918
Consider the decimal representations below. \(x = 1.23232323\ldots\), where the block “23” repeats forever \(y = 1.232232223\ldots\), where each successive block before a \(3\) contains one more \(2\) than the previous block 1. Decide whether each number is rational or irrational. 2. Justify each decision using the decimal representation. 3. Write the rational number as a fraction in lowest terms.

Hints

- What distinguishes a repeating decimal from a nonrepeating decimal? - To convert a repeating block of two digits, multiply by \(100\) and subtract the original number. - A pattern governed by a rule is not necessarily periodic.

Solution

1. The decimal for \(x\) repeats: \(x = 1.\overline{23}\). Therefore, \(x\) is rational. 2. The decimal for \(y\) is nonterminating and nonrepeating because the number of consecutive \(2\)s keeps increasing. Therefore, \(y\) is irrational. 3. Let \(x = 1.\overline{23}\). Then \(100x = 123.\overline{23}\). Subtracting gives \(99x = 122\), so \(x = \frac{122}{99}\). The numerator and denominator have no common factor, so the fraction is in lowest terms.

Answer

1. \(x\) is rational, and \(y\) is irrational. 2. The decimal for \(x\) repeats, while the decimal for \(y\) is nonterminating and nonrepeating. 3. \(x = \frac{122}{99}\)
5498188
Convert \(0.1\overline{6}\) to a fraction in lowest terms.

Hints

- Separate the nonrepeating part from the repeating part. - Create two shifted equations whose repeating tails match. - Reduce after solving for the variable.

Solution

1. Let \(x=0.1\overline{6}\). 2. Shift past the nonrepeating digit: \(10x=1.\overline{6}\). 3. Shift one more place: \(100x=16.\overline{6}\). 4. Subtract: \(100x-10x=15\), so \(90x=15\). 5. Thus, \(x=\frac{15}{90}=\frac{1}{6}\).

Answer

\(0.1\overline{6}=\frac{1}{6}\)
5498198
Convert \(0.42\overline{3}\) to a fraction in lowest terms.

Hints

- Count the nonrepeating digits before the bar. - Build two equations that differ by one complete period. - Simplify the final fraction carefully.

Solution

1. Let \(x=0.42\overline{3}\). 2. Shift past the two nonrepeating digits: \(100x=42.\overline{3}\). 3. Shift one more digit: \(1000x=423.\overline{3}\). 4. Subtract: \(1000x-100x=381\), so \(900x=381\). 5. Therefore, \(x=\frac{381}{900}=\frac{127}{300}\).

Answer

\(0.42\overline{3}=\frac{127}{300}\)
5498208
Convert \(1.2\overline{45}\) to a fraction in lowest terms.

Hints

- Account separately for the prefix and the two-digit period. - Align the repeating blocks before subtracting. - Expect an improper fraction because the decimal is greater than \(1\).

Solution

1. Let \(x=1.2\overline{45}\). 2. Shift past the one nonrepeating digit: \(10x=12.\overline{45}\). 3. Shift two additional places: \(1000x=1245.\overline{45}\). 4. Subtract: \(1000x-10x=1233\), so \(990x=1233\). 5. Thus, \(x=\frac{1233}{990}=\frac{137}{110}\).

Answer

\(1.2\overline{45}=\frac{137}{110}\)
5498228
Riley tries to convert \(0.\overline{27}\) by writing \(x=0.\overline{27}\) \(10x=2.\overline{72}\) and then subtracting. Identify the error, choose the correct power of \(10\), and complete the conversion.

Hints

- Compare the length of the repeating block with the number of places shifted. - The infinite tails must match exactly before subtraction. - Reduce the fraction after correcting the setup.

Solution

1. Multiplying by \(10\) shifts only one digit, so the repeating tails do not align. 2. The period has \(2\) digits, so use \(100x=27.\overline{27}\). 3. Subtracting \(x=0.\overline{27}\) gives \(99x=27\). 4. Therefore, \(x=\frac{27}{99}=\frac{3}{11}\).

Answer

Riley shifted by too few places. The correct conversion is \(0.\overline{27}=\frac{3}{11}\).
5498248
For \(x=0.4\overline{2}\), the conversion uses \(100x-10x=\square\). Find the number that belongs in the box, then convert \(x\) to a fraction in lowest terms.

Hints

- Write both shifted decimals explicitly. - Check that the repeating parts line up. - Subtract the finite parts after the tails cancel.

Solution

1. \(10x=4.\overline{2}\) and \(100x=42.\overline{2}\). 2. Subtracting gives \(100x-10x=42.\overline{2}-4.\overline{2}=38\). 3. Thus, \(90x=38\). 4. Therefore, \(x=\frac{38}{90}=\frac{19}{45}\).

Answer

The box contains \(38\), and \(0.4\overline{2}=\frac{19}{45}\).
5498268
Explain why \(0.\overline{124}\) can first be written with denominator \(999\), then convert it to a fraction in lowest terms.

Hints

- Relate the number of repeating digits to a power of \(10\). - Notice what coefficient remains after subtracting the original variable. - Check for a common factor only after forming the fraction.

Solution

1. Let \(x=0.\overline{124}\). 2. A \(3\)-digit shift gives \(1000x=124.\overline{124}\). 3. Subtracting gives \((1000-1)x=124\), so \(999x=124\). 4. Therefore, \(x=\frac{124}{999}\). 5. Since \(124\) and \(999\) share no common factor greater than \(1\), the fraction is already in lowest terms.

Answer

The denominator \(999\) comes from \(1000-1\). Thus, \(0.\overline{124}=\frac{124}{999}\).
5498288
Convert \(1.24\overline{9}\) to a fraction in lowest terms. Then write an equivalent terminating decimal.

Hints

- Align the repeating nines using two shifts. - Reduce the resulting fraction fully. - Check whether the reduced denominator produces a terminating decimal.

Solution

1. Let \(x=1.24\overline{9}\). 2. \(100x=124.\overline{9}\) and \(1000x=1249.\overline{9}\). 3. Subtracting gives \(900x=1125\). 4. Thus, \(x=\frac{1125}{900}=\frac{5}{4}\). 5. Therefore, the equivalent terminating decimal is \(1.25\).

Answer

\(1.24\overline{9}=\frac{5}{4}=1.25\)
5498318
Solve for \(x\): \(x+0.\overline{4}=\frac{5}{6}\) Write \(x\) as a fraction in lowest terms.

Hints

- Replace the repeating decimal with an exact fraction first. - Isolate the unknown after the conversion. - Use a common denominator for the remaining subtraction.

Solution

1. Convert \(0.\overline{4}=\frac{4}{9}\). 2. Subtract to isolate \(x\): \(x=\frac{5}{6}-\frac{4}{9}\). 3. Using denominator \(18\), \(x=\frac{15}{18}-\frac{8}{18}=\frac{7}{18}\).

Answer

\(x=\frac{7}{18}\)
5498348
Find the exact average of \(0.\overline{3}\) and \(0.\overline{6}\). Write the result as a fraction.

Hints

- Express both repeating decimals as fractions. - Find their sum before applying the meaning of average. - Keep the calculation exact.

Solution

1. Convert \(0.\overline{3}=\frac{1}{3}\) and \(0.\overline{6}=\frac{2}{3}\). 2. Their sum is \(\frac{1}{3}+\frac{2}{3}=1\). 3. Divide by \(2\): the average is \(\frac{1}{2}\).

Answer

\(\frac{1}{2}\)
5498358
An equilateral triangular frame has side length \(0.\overline{27}\,\text{m}\). Convert the side length to a fraction, then find the exact perimeter in meters.

Hints

- Convert the repeating side length before using the shape information. - Use the number of equal sides in the frame. - State both requested exact values with units.

Solution

1. Convert \(0.\overline{27}=\frac{27}{99}=\frac{3}{11}\). 2. An equilateral triangle has \(3\) equal sides. 3. The perimeter is \(3\cdot\frac{3}{11}=\frac{9}{11}\,\text{m}\).

Answer

Side length: \(\frac{3}{11}\,\text{m}\) Perimeter: \(\frac{9}{11}\,\text{m}\)
5498368
A ferry trip lasts \(1.\overline{6}\) hours. a) Convert the time to a fraction of an hour. b) Convert the exact time to minutes.

Hints

- Convert the repeating time to an exact fraction first. - Use the standard relationship between hours and minutes. - Check whether the converted number of minutes is reasonable for more than one hour.

Solution

1. Let \(x=1.\overline{6}\). Then \(10x-x=15\), so \(9x=15\). 2. Thus, \(x=\frac{15}{9}=\frac{5}{3}\) hours. 3. Multiply by \(60\) minutes per hour: \(\frac{5}{3}\cdot60=100\) minutes.

Answer

a) \(\frac{5}{3}\) hours b) \(100\) minutes
5498378
Order the numbers from least to greatest: \(0.\overline{45}\), \(\frac{5}{11}\), and \(0.46\). Convert the repeating decimal to justify any equality.

Hints

- Convert the repeating decimal before comparing all three forms. - Look for two representations of the same value. - Compare the remaining decimal by place value.

Solution

1. Convert \(0.\overline{45}=\frac{45}{99}=\frac{5}{11}\). 2. The first two numbers are equal. 3. \(\frac{5}{11}=0.4545\ldots<0.46\). 4. Therefore, the two equal values come before \(0.46\).

Answer

\(0.\overline{45}=\frac{5}{11}<0.46\)
5498388
Determine whether \(0.1\overline{8}\) is less than, equal to, or greater than \(\frac{17}{90}\). Show an exact conversion.

Hints

- Use two shifts because the decimal has a prefix and a period. - Align the repeating tails exactly. - Compare only after obtaining the reduced fraction.

Solution

1. Let \(x=0.1\overline{8}\). 2. Then \(10x=1.\overline{8}\) and \(100x=18.\overline{8}\). 3. Subtracting gives \(90x=17\). 4. Therefore, \(x=\frac{17}{90}\), so the values are equal.

Answer

\(0.1\overline{8}=\frac{17}{90}\)
5498398
Convert \(2.03\overline{12}\) to a fraction in lowest terms.

Hints

- Count the prefix digits and the repeating digits separately. - Build the smaller shift first, then move one full period farther. - Reduce the improper fraction at the end.

Solution

1. Let \(x=2.03\overline{12}\). 2. Shift past the \(2\) nonrepeating digits: \(100x=203.\overline{12}\). 3. Shift one full period farther: \(10000x=20312.\overline{12}\). 4. Subtracting gives \(9900x=20109\). 5. Thus, \(x=\frac{20109}{9900}=\frac{6703}{3300}\).

Answer

\(2.03\overline{12}=\frac{6703}{3300}\)
5498408
Convert \(0.00\overline{72}\) to a fraction in lowest terms. Explain how the two nonrepeating zeros affect the denominator.

Hints

- Shift past both zeros before aligning a complete period. - Compare the two powers of \(10\) used in the subtraction. - Reduce only after forming the exact fraction.

Solution

1. Let \(x=0.00\overline{72}\). 2. Then \(100x=0.\overline{72}\) and \(10000x=72.\overline{72}\). 3. Subtracting gives \(9900x=72\). 4. Thus, \(x=\frac{72}{9900}=\frac{2}{275}\). 5. The two prefix places contribute two factors of \(10\) to the unreduced denominator.

Answer

\(0.00\overline{72}=\frac{2}{275}\)
5498418
To convert \(0.58\overline{3}\), a student writes \(1000x-x=583\). Explain why subtracting \(x\) is incorrect, then complete the conversion.

Hints

- Write the shifted decimals and compare the positions of the repeating digits. - The smaller multiplier must move past the entire nonrepeating prefix. - Subtract only equations with identical infinite tails.

Solution

1. The decimal has two nonrepeating digits, so \(x\) and \(1000x\) do not have aligned repeating tails. 2. Use \(100x=58.\overline{3}\) and \(1000x=583.\overline{3}\). 3. Subtracting gives \(900x=525\). 4. Therefore, \(x=\frac{525}{900}=\frac{7}{12}\).

Answer

The repeating tails align for \(1000x-100x\), not \(1000x-x\). Thus, \(0.58\overline{3}=\frac{7}{12}\).
5498428
A game displays a win probability of \(0.\overline{36}\). Convert the probability to a fraction in lowest terms, then state the exact number of expected wins out of \(55\) plays if the probability were matched exactly.

Hints

- Convert the repeating probability before using the number of plays. - Reduce the fraction to make the multiplication simpler. - Interpret the product in the context of wins.

Solution

1. Convert \(0.\overline{36}=\frac{36}{99}=\frac{4}{11}\). 2. Multiply by \(55\): \(55\cdot\frac{4}{11}=5\cdot4=20\). 3. The exact fraction is \(\frac{4}{11}\), corresponding to \(20\) wins out of \(55\) plays.

Answer

Probability: \(\frac{4}{11}\) Expected wins out of \(55\): \(20\)
5498438
A model railroad scale uses \(0.\overline{24}\,\text{in}\) of model length for each foot of actual length. a) Convert the scale factor to a fraction. b) Find the model length for an actual length of \(33\,\text{ft}\).

Hints

- Rewrite the repeating scale factor exactly. - Preserve the units attached to the factor. - Look for cancellation when applying the factor to the actual length.

Solution

1. Convert \(0.\overline{24}=\frac{24}{99}=\frac{8}{33}\). 2. Multiply by \(33\,\text{ft}\): \(33\cdot\frac{8}{33}=8\). 3. The model length is \(8\,\text{in}\).

Answer

a) \(\frac{8}{33}\,\text{in}\) per foot b) \(8\,\text{in}\)
5498448
Find the smallest positive whole number \(n\) for which \(n\cdot0.\overline{15}\) is a whole number. State that whole-number product.

Hints

- Convert the repeating decimal to lowest terms. - Focus on what must happen to the denominator for the product to be a whole number. - Use the smallest multiplier that provides all needed factors.

Solution

1. Convert \(0.\overline{15}=\frac{15}{99}=\frac{5}{33}\). 2. The product is \(n\cdot\frac{5}{33}\). 3. Since \(5\) and \(33\) are relatively prime, the smallest positive \(n\) that cancels the denominator is \(33\). 4. The product is \(33\cdot\frac{5}{33}=5\).

Answer

\(n=33\), and the product is \(5\).
5498458
Which repeating decimal equals \(\frac{14}{37}\)? Verify your choice by conversion. A. \(0.\overline{147}\) B. \(0.\overline{378}\) C. \(0.\overline{518}\)

Hints

- A three-digit repeating block first gives a denominator of \(999\). - Test each option by reducing its block-over-nines fraction. - Stop once the reduced fraction matches exactly.

Solution

1. Convert choice B: \(0.\overline{378}=\frac{378}{999}\). 2. Divide numerator and denominator by \(27\): \(\frac{378}{999}=\frac{14}{37}\). 3. Therefore, choice B is the required decimal.

Answer

B. \(0.\overline{378}\)
5498488
Convert both decimals and compare them: \(A=0.\overline{27}\) \(B=0.0\overline{27}\) How many times as large is \(A\) as \(B\)?

Hints

- Notice the effect of placing one zero before the repeating block. - Convert each decimal with its correct place value. - Compare the fractions using a quotient.

Solution

1. \(A=\frac{27}{99}=\frac{3}{11}\). 2. The extra nonrepeating zero shifts the value one place right, so \(B=\frac{27}{990}=\frac{3}{110}\). 3. \(\frac{A}{B}=\frac{3/11}{3/110}=10\). 4. Therefore, \(A\) is \(10\) times as large as \(B\).

Answer

\(A=\frac{3}{11}\), \(B=\frac{3}{110}\), and \(A\) is \(10\) times as large as \(B\).
5498498
Compute exactly: \(0.\overline{09}+0.\overline{90}\) Convert both addends to fractions and explain the pattern in the result.

Hints

- Keep the leading zero in the first repeating block. - Convert both two-digit periods using the same initial denominator. - Look at how the numerators combine.

Solution

1. \(0.\overline{09}=\frac{9}{99}=\frac{1}{11}\). 2. \(0.\overline{90}=\frac{90}{99}=\frac{10}{11}\). 3. Their sum is \(\frac{1}{11}+\frac{10}{11}=1\). 4. The repeating blocks add to \(99\), matching the unreduced denominator \(99\).

Answer

\(0.\overline{09}+0.\overline{90}=1\)
5498508
Convert \(4.\overline{05}\) to a fraction in lowest terms.

Hints

- Treat the zero as part of the two-digit period. - Subtract the whole original decimal after shifting one complete block. - Check whether the final numerator shares a factor with \(99\).

Solution

1. Let \(x=4.\overline{05}\). 2. Then \(100x=405.\overline{05}\). 3. Subtracting the original equation gives \(99x=401\). 4. Therefore, \(x=\frac{401}{99}\), which is in lowest terms.

Answer

\(4.\overline{05}=\frac{401}{99}\)
5498518
A student writes \(0.1\overline{2}=\frac{12}{99}\). Explain why this fraction treats the decimal incorrectly, then find the correct fraction.

Hints

- Identify exactly which digits lie under the bar. - Compare the claimed fraction with the decimal it would actually produce. - Use separate shifts for the prefix and the period.

Solution

1. The expression \(\frac{12}{99}\) represents \(0.\overline{12}\), where both digits repeat. 2. In \(0.1\overline{2}\), only the digit \(2\) repeats. 3. Let \(x=0.1\overline{2}\). Then \(10x=1.\overline{2}\) and \(100x=12.\overline{2}\). 4. Subtracting gives \(90x=11\), so \(x=\frac{11}{90}\).

Answer

The student repeated the prefix digit incorrectly. The correct value is \(0.1\overline{2}=\frac{11}{90}\).
5498538
Which fraction equals \(0.07\overline{4}\)? Show the conversion. A. \(\frac{37}{500}\) B. \(\frac{67}{900}\) C. \(\frac{74}{999}\)

Hints

- Count the two prefix digits before the repeating digit. - Use two equations whose repeating tails are identical. - Compare the exact fraction with the choices.

Solution

1. Let \(x=0.07\overline{4}\). 2. Then \(100x=7.\overline{4}\) and \(1000x=74.\overline{4}\). 3. Subtracting gives \(900x=67\). 4. Thus, \(x=\frac{67}{900}\), which is choice B.

Answer

B. \(\frac{67}{900}\)
5498558
Find the exact value of \(1.\overline{3}-0.\overline{81}\) as a fraction in lowest terms.

Hints

- Convert each repeating decimal independently. - Reduce before finding a common denominator. - Keep the final subtraction exact.

Solution

1. Convert \(1.\overline{3}=\frac{4}{3}\). 2. Convert \(0.\overline{81}=\frac{81}{99}=\frac{9}{11}\). 3. Subtract using denominator \(33\): \(\frac{4}{3}-\frac{9}{11}=\frac{44}{33}-\frac{27}{33}=\frac{17}{33}\).

Answer

\(\frac{17}{33}\)
5144578
Two numbers are given by their decimal representations. \(x = 0.\overline{12}\) \(y = 0.121122111222\ldots\) a) Convert \(x\) to a fraction \(\frac{p}{q}\) in lowest terms. b) Explain why \(y\) is irrational. c) Give a rational decimal \(z\) such that \(y < z < x\). Justify your choice by comparing decimal digits.

Hints

- Convert a repeating two-digit block by multiplying by \(100\) and subtracting. - Compare decimals digit by digit from left to right. - Every terminating decimal is rational.

Solution

1. Since \(x = 0.121212\ldots\), \(x = \frac{12}{99} = \frac{4}{33}\). 2. The decimal for \(y\) contains blocks of \(1\)s and \(2\)s whose lengths keep increasing. Therefore, no fixed block repeats forever. The decimal is nonterminating and nonrepeating, so \(y\) is irrational. 3. Compare \(x = 0.121212\ldots\) with \(y = 0.121122\ldots\). At the fourth decimal place, \(x\) has \(2\) and \(y\) has \(1\), so \(y < x\). 4. One rational number between them is \(z = 0.1212\). Indeed, \(0.121122\ldots < 0.121200\ldots < 0.121212\ldots\).

Answer

a) \(x = \frac{4}{33}\) b) \(y\) is irrational because its increasing block lengths make its decimal expansion nonterminating and nonrepeating. c) One example is \(z = 0.1212\), since \(y < 0.1212 < x\).
5498468
The digit \(d\) satisfies \(0.2\overline{d}=\frac{13}{45}\). Find \(d\) by converting the repeating decimal in terms of \(d\).

Hints

- Keep the unknown digit symbolic while shifting the decimal. - Express both sides with the same denominator after conversion. - Compare the resulting numerators.

Solution

1. Let \(x=0.2\overline{d}\). 2. Then \(10x=2.\overline{d}\) and \(100x=20+d+0.\overline{d}\). 3. Subtracting gives \(90x=18+d\). 4. Since \(x=\frac{13}{45}=\frac{26}{90}\), \(18+d=26\). 5. Therefore, \(d=8\).

Answer

\(d=8\)
5498478
Let \(a\) and \(b\) be digits, and let \(N=10a+b\). Derive a fraction rule for \(0.\overline{ab}\) in terms of \(N\). Then use the rule to convert \(0.\overline{62}\).

Hints

- Represent the two-digit block as one whole number. - Shift exactly one full period. - Keep the block symbolic until after the subtraction.

Solution

1. Let \(x=0.\overline{ab}\). 2. Then \(100x=N.\overline{ab}\). 3. Subtracting gives \(99x=N\), so \(x=\frac{N}{99}\). 4. For \(62\), \(N=62\), so \(0.\overline{62}=\frac{62}{99}\).

Answer

The rule is \(0.\overline{ab}=\frac{10a+b}{99}\). Therefore, \(0.\overline{62}=\frac{62}{99}\).
5498528
Two methods are proposed for converting \(3.1\overline{24}\). a) Use \(x=3.1\overline{24}\) and aligned subtraction to convert the decimal. b) Decompose the decimal as \(3+\frac{1}{10}+0.0\overline{24}\), convert the repeating part, and show that this method gives the same fraction. Give the fraction in lowest terms.

Hints

- In the first method, choose shifts that place identical repeating tails under each other. - In the second method, separate the whole, terminating, and repeating portions. - Compare the reduced results rather than their unreduced denominators.

Solution

1. a) \(1000x=3124.\overline{24}\) and \(10x=31.\overline{24}\), so \(990x=3093\). Thus \(x=\frac{3093}{990}=\frac{1031}{330}\). 2. b) Let \(y=0.0\overline{24}\). Then \(1000y-10y=24\), so \(y=\frac{24}{990}=\frac{4}{165}\). 3. \(3+\frac{1}{10}+\frac{4}{165}=\frac{990+33+8}{330}=\frac{1031}{330}\), matching part a).

Answer

a) \(\frac{1031}{330}\) b) The decomposition also gives \(\frac{1031}{330}\).

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