what is 18.39 x 2.5

Question

What is the sum of 18.39 x 2.5

Answer 1

The product 18.39*2.5 can be calculated in different ways. The way I like best is using the fact that 4*2.5=10 so 2.5=10/4. This means we can multiply by 10 (move the decimal place one place to the right then divide by 4. So we have: 183.9/4=45.975.

Another way is to double 18.39 and halve it and add the two results together: 36.78+9.195=45.975. This works because 2.5 is 2+0.5 which 2+1/2 (sum of double and half).