Question

Find the sum of all numbers from 1 to 140 which are divisible by 4.

Answer 1

The numbers from 1 to 140 which are divisible by 4 are 4, 8, 12, ... 140

This sequence is an A.P. with a = 4, d = 8 – 4 = 4, tn = 140

(\therefore) The sum of all numbers from 1 to 140 which are divisible by 4 is 2520.