Fractions » Multiplying and dividing fractions

Multiplying

Multiplying is actually easier than adding and subtracting.
You can immediately do numerator × numerator and denominator × denominator.
You do NOT have to make the denominators equal.
Remember that when multiplying with a whole number 5 = 51.

Examples

45 × 38 = 4 × 35 × 8 = 1240 = 310
6 × 37 = 6 × 31 × 7 = 187 = 247   (Remember 6 = 61)
325 × 56 = 175 × 56 = 17 × 55 × 6 = 8530 = 176 = 256

Last example:
Remember that 3 is the same as 155. So 325 = 155 + 25 = 175.

Dividing

The rule is: 'Dividing by a fraction is multiplying by the reciprocal.'
The reciprocal of a fraction is the inverse of a fraction. So where the numerator and the denominator are swapped.
For example: : 27 is the same as × 72.

Example

35 : 78 = 35 × 87 = 3 × 85 × 7 = 2435