Conversion Between Recurring Decimals and Fractions

Conversion Between Recurring Decimals and Fractions

IP 1

Steps to Convert Recurring Decimals to Fractions

Step 1: Assign the recurring decimal to a variable (represented by letters) with unknown value, e.g., let \(x=0.\dot{3}\).

Step 2: If there are \(m\) nonrepeating decimal places followed by a repeating block of \(n\) digits, form \(10^{m+n}x\) and \(10^m x\). Here \(m=0\), \(n=1\).

\(10\):\(10x=3.\dot{3}\).

Step 3: Subtract \(10^m x\) from \(10^{m+n}x\) to cancel the identical recurring tails. The resulting equation has integer coefficients.

\(10x-x=3.\dot{3}-0.\dot{3}\)

Step 4: Solve for \(x\), the value of the recurring decimal expressed as \(\frac{p}{q}\).

\(\begin{align} & 9x=3 \\ & x=\frac{1}{3} \end{align}\)

Exam check

Check by dividing: \(1\div3=0.\dot{3}\). When a digit comes before the repeating block, use two powers of ten. For \(x=0.1\dot{2}\dot{7}\): \(1000x=127.\dot{2}\dot{7}\) and \(10x=1.\dot{2}\dot{7}\), so \(990x=126\) and \(x=\dfrac{7}{55}\). Subtracting \(x\) from \(100x\) also cancels the tail but gives \(99x=12.6\), which is not a whole number; \(1000x-10x\) keeps whole numbers.

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Answer:For example, \(0.\overline3=1/3\). In general subtract \(10^m x\) from \(10^{m+n}x\), where \(m\) is the nonrecurring prefix length and \(n\) is the recurring block length.

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