PET 2026 · CSAT

Convert recurring decimals to fractions

Align the repeating tail, subtract, reduce to lowest terms and check reciprocals

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MINDMAPS FOR UPSCPET 2026 · VISUAL REVISION

Convert recurring decimals to fractions

Align the repeating tail, subtract, reduce to lowest terms and check reciprocals

Process flow
Recurring decimals and fraction form
  1. Step 1: Identify the repeating block

    • Distinguish a pure recurring decimal (0.232323…) from a mixed one (0.23333…).
    • Count non-repeating digits after the decimal point and digits in the repeating block.
    • A reduced fraction p/q terminates only when q has no prime factors other than 2 and 5.
  2. Step 2: Multiply to align tails

    • For x = 0.232323…, two digits repeat, so multiply by 10² = 100 to get 100x = 23.232323…
    • For y = 0.23333…, one non-repeating digit precedes one repeating digit.
    • Multiply y by 10 and 100 so both shifted forms, 10y = 2.333… and 100y = 23.333…, share the same tail.
  3. Step 3: Subtract and reduce

    • Subtract aligned equations: 100x − x = 23 gives 99x = 23, so x = 23/99.
    • For y: 100y − 10y = 21 gives 90y = 21, which reduces by gcd 3 to y = 7/30.
    • Always reduce before summing terms: for p/q = 23/99 and r/s = 7/30, p + q + r + s = 159.
  4. Step 4: Check proper and reciprocal forms

    • For positive integers a,b: a/b is proper if a < b and improper if a ≥ b.
    • Inverting a non-zero fraction swaps numerator and denominator: reciprocal of a/b is b/a.
    • Reciprocal b/a is proper only when a > b; thus 9/7 has the proper reciprocal 7/9.
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Practise this concept · संबंधित प्रश्न

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25 Oct · Shift 2 · 2026

30 Oct · Shift 1 · 2026

Sources & study notes · स्रोत

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