How Do I Multiply Rational Numbers?

Rational numbers are the numbers which can be written in p/q form. In other words when two integers are written in ratio form then they are known as rational numbers like 1/2, 4/6 etc. Now, multiplication of any integers have two basic rules. The first rule is that multiplication of two same sign numbers give the positive product while the different signs give negative results.

When you multiply rational numbers then always multiply the upper integers with each other and lower integers with each other. Try to cancel the numbers if there is a common number between them. If you find some difficulty then you can first convert the integers into prime numbers. For example,

(3/5) x (10/9)

= 30/45

If further division is required then both these numbers are divisible by 5.

= 6/9

= 2/3

As upper integers are 3 and 10 therefore multiply 3 with 10 and 5 with 9. If you want further convenience then convert the numbers into prime number first as 10 = 2 x5 and 9 = 3 x3

Therefore,

(3/5) x (10/9)

= (3/5) x (2 x 5/3 x 3)

Now 3 will cancel out with 3 and 5 with 5 and you are left with 2/3.