Question

Find the sum of all the integers from 1 to 100 that are not multiples of 7

Answer 1

4343

Explanation:

To find multiple of 7 from 1 to 100,

Take the quotient of 100/7=14

n=100 (number of terms)

n=100-14 (Without Multiple of 7=number of terms - multiple of 7)

=>n=86

Sum of 1 to 100 => Sn = n/2(a + an)

=> Sn = 86/2(1+100)

=> Sn = 43(101)

=> Sn = 4343