NUMBAT OER - Open Educational Resources

4. Decimals

In section 2, you saw how to convert an improper fraction (one where the numerator is larger than the denominator) into a mixed number. The denominator divides into the numerator to yield a whole number and a fraction, whose numerator is the remainder from the division:

21  = 5  1
4 4

If we divide the numerator of the fraction part of the mixed number by the denominator, we convert the fraction into a decimal:

5  1  = 5.25
4

The decimal result is usually spoken as 'five point two five' (not 'five point twenty-five').

A decimal number normally comprises a whole number (that can be zero as in the fractions table in section 4.3) and the decimal part (the part of the number that is less than one). The usual separator for these two parts of the number is a period (e.g. '2.345'), although in Continental Europe a comma (e.g. '2,345') is used (for this reason, it is advisable to represent thousands by using a space separator, as in '2 345', rather than a comma). You might occasionally encounter a redundant notation like 3·976, and in the UK a hyphen or dash is used as the separator when writing currency amounts (e.g. £37-58).