Question

Find the sum of all natural numbers between 602 and 902 which are not divisible by 4?

Answer 1

First find the sum of all the natural’s number between 602 and 902 

Here a = 603, d = 1, l = 901

Find the sum of all the numbers between 602 and 902 which are divisible by 4. 

Here a = 604; l = 900; d = 4

Sum of the numbers which are not divisible by 4 = S_n1 – S_n2 

= 224848 – 56400 

= 168448 

Sum of the numbers = 168448