Fraction to decimal
Enter numerator and denominator: get the corresponding decimal number.
What it's for
A fraction says one thing only: divide the number on top by the one underneath. You need it when a number arrives written as a fraction but you need it as a decimal, which is nearly every practical case: a measurement to mark on a tape, a ratio to put in a spreadsheet, a mark, a quantity to weigh on scales, reading a half-inch spanner.
The point school tends to skip
Not every fraction gives a decimal that ends. 3/4 is 0.75 and stops; 1/3 is 0.333… and never stops. The rule for knowing in advance is precise: reduce the fraction to its lowest terms and look at the denominator. If it contains only the factors 2 and 5 (2, 4, 5, 8, 10, 16, 20, 25, 40…) the decimal ends; if it contains any other prime factor (3, 7, 11, 13…) the decimal repeats, going on forever with a recurring group of digits.
Here a repeating decimal isn't cut short: the digits that repeat have a line over them, as in an exercise book, and under the result the page says which digits repeat, writes the same number with the repeating part in brackets (1/3 = 0.(3), 1/7 = 0.(142857)) and gives the rounded value, for when you only need the digits. When the repeating part is longer than 60 digits (1/97 has 96) the first 60 are shown, and the page says how long it is.
The fractions you actually meet
1/2 = 0.5 · 1/3 = 0.333… · 1/4 = 0.25 · 1/5 = 0.2 · 1/8 = 0.125 · 2/3 = 0.666… · 3/4 = 0.75 · 1/16 = 0.0625. Powers of two (half, quarter, eighth, sixteenth) always give decimals that end, which is why they're used in inch measurements and in recipes: you can halve them as many times as you like without ever losing anything.
Nearby tools
The opposite direction, from a decimal to the simplest fraction that represents it, is Decimal to fraction. To work out a fraction of a quantity («three quarters of 240») there is Fraction of a number, and to turn the fraction into a percentage Percentage calculator. To reduce a fraction to lowest terms with the steps, or to add, subtract, multiply and divide two fractions, there is Simplify Fractions.