Numbers

3. Decimals

3.3. Converting fractions to decimals

To convert a fraction to a decimal, we divide the numerator (the number above the fraction bar) by the denominator (the number below).

For example, let’s find the decimal value of 1/4 (one fourth, or a quarter).

Using a calculator, divide 1 by 4 (1 ÷ 4):

1 ÷ 4 = 0.25

0.25 is 1/4 expressed as a decimal.

0.25 is the same value as 1/4, e.g. one quarter of a cake

Calculators: Most mobile phones include a 'Calculator' app, as do Windows and Mac OS operating systems on computers and laptops. There are also online calculators you might find useful, for example Calculator.net.

Try it out: 1

If we take one quarter slice away, what is the decimal value of the remaining 3 slices of cake?

There are 3/4 (three quarters) remaining. To express this as a decimal, we divide the numerator (3) by the denominator (4).

3 ÷ 4 = 0.75

so 0.75 is 3/4 expressed as a decimal.

Alternatively, and remembering that fractions are parts of a whole, we could have subbtracted the value that we already knew (1/4 = 0.25), from the whole, to find the remaining value.The whole is 1.00, in decimal terms, so subtracting 0.25 from this tells us that 0.75 remains.

1.00 - 0.25 = 0.75


Try it out: 2
one and a half green apples

How would you express one and a half (1½) as a decimal?

Convert the fraction (1/2) to a decimal: 1 ÷ 2 = 0.5

Add this to the whole (1): 1 + 0.5 = 1.5

One and a half (1½) is 1.5 as a decimal.