Question

Simplify the ratio 18:30

Answer 1

find a number that divides into both 18 and 30

e.g 21:56
7 divides into both so divide both by 7 = 3:8

You need to find the largest number that divide into both...

Answer 2

Is it 6:10

Answer 3

you can see that 6:10 can also be simplified - so no - there is a higher number that divides them both

Answer 4

3:5 ?

Answer 5

Well done

Answer 6

Thank you

Answer 7

The number you want is called the highest common factor (HCF)

There are a number of ways to find it - for more complicated examples it may not be so apparent as this one.

http://en.wikipedia.org/wiki/Greatest_common_divisor