Question

How many multiples of 9 lies between 70and 700? Find the sum of these multiple of 9..

Answer 1

Answer:

Numbers between 70 and 700 are

71, 72, 73, 74........699

Which are multiples of 9 are

72, 81, 90, .......... 693

an = a + (n - 1)d

693 = 72 + (n - 1)(9)

693 - 72 = (n - 1)(9)

621 = (n - 1)(9)

n - 1 = 621/9

n - 1 = 69

n = 69 + 1

n = 70