Express $0.29\overline{56}$ in the form $\frac{p}{q}$ (vulgar fraction)
Aptitude
Decimal Fraction
Difficulty: Medium
Choose an option
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A$\frac{2956}{1000}$
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B$\frac{2956}{10000}$
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C$\frac{2927}{9900}$
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DNone of these
Answer
Correct Answer: $\frac{2927}{9900}$
Explanation
Concept & Formula
To convert a mixed recurring decimal into a fraction, subtract the non-repeating digits from the entire sequence to find the numerator. For the denominator, append as many $9$s as there are repeating digits, followed by as many $0$s as there are non-repeating digits after the decimal point.
$$ \text{Fraction} = \frac{\text{Complete Number} - \text{Non-repeating Part}}{\text{9s (for repeating digits)} \text{0s (for non-repeating digits)}} $$
Step-by-Step Solution
Given the decimal: $0.29\overline{56}$
1. Identify the components after the decimal point:
- Complete sequence: $2956$
- Non-repeating digits: $29$ (two digits)
- Repeating digits: $56$ (two digits under the bar)
2. Compute the numerator:
$$ 2956 - 29 = 2927 $$
3. Compute the denominator:
- Two repeating digits $\rightarrow$ two $9$s ($99$)
- Two non-repeating digits $\rightarrow$ two $0$s ($00$)
- Denominator = $9900$
4. Combine to form the fraction:
$$ \frac{2927}{9900} $$
Exam Strategy & Shortcut
Look at the bar position instantly. Since there are two repeating digits ($56$) and two non-repeating digits ($29$), the denominator must be $9900$. This immediately eliminates options (a) and (b). A quick subtraction $2956 - 29 = 2927$ confirms option (c) directly.
Common Pitfall
Students often place the entire number over $10000$ (Option b) by treating it as a standard terminating decimal, or they forget to subtract the non-repeating part ($29$) from the numerator. Remember, the bar changes the entire denominator logic.
Final Answer
Therefore, the correct answer is $\frac{2927}{9900}$.