Question

find the sum of integers between 100and200......that are not divisible by 9

Answer 1

Sum of integers between 100 and 200 that are divisible by 9 = 108 + 117 + 126 + … + 198. Here this is the sequence of an A.P. where first term;a = 108, common difference;d = 9. Here nth term of an A.P. is 198, so we have; So sum of 11 terms is given by; 108 + 117 + 126 + … + 198 = So the sum of integers .