Question

Find the sum of integers from 1 to 400 which are divisible by 3 and 5.

Answer 1

To find the sum of integers that are divisible by 3 and 5 we need to check for LCM of 3 and 5
LCM of 3 and 8 is 15.
So integers between 1 to 400 that are divisible by 3 and 5 will be = 15, 30, 45...........390
Sum of these integers = 15( 1+2+3….26)
= 15 x 26 x 27
2
= 15 x 13 x 27
= 5265