How it works
A terminating decimal is a fraction over a power of 10: 0.625 is 625/1000. Dividing top and bottom by their greatest common factor (125) gives 5/8.
Repeating decimals are fractions too. Enter the repeating block in parentheses (0.(3) for 0.333…, or 0.1(6) for 0.1666…) and the calculator returns the exact fraction, 1/3 or 1/6.
Formula
0.abc = abc/1000, then reduce by the GCF. 0.(r) = r ÷ (10^k − 1) for a k-digit repeating block.
Questions people ask
How do I convert 0.75 to a fraction?
0.75 = 75/100. The GCF of 75 and 100 is 25, so it reduces to 3/4.
How do I convert a repeating decimal like 0.272727…?
Let x = 0.2727…, so 100x = 27.2727…. Subtracting gives 99x = 27, so x = 27/99 = 3/11. Enter it here as 0.(27).
Why is 0.999… equal to 1?
Using the same method, x = 0.999… gives 10x − x = 9, so x = 1. The two notations name the same number. Try entering 0.(9).