Question

Find the sum of numbers from 1 to 100 which are divisible by 2 and 9.

Answer 1

Step-by-step explanation:

no. between 1 and 100 divisible by 9& 2 both = 18, 36, 54 ,72 ,90

sum = 18 + 36+54+72+90 = 270

2nd way

AP = 18,36, 54 , 72, 90

d = 18 , a = 18 ,last term = 90

sum = 5/2 ( 18 + 90) = 270

Answer 2

Answer:

2874

Step-by-step explanation:

divisible by 2 = 2,4,6 , ..., 100 = 2×50/2×51 = 2550

divisible by 9 = 9,18,27 , ..., 99 = 9 ×11×12/2 = 594

divisible by 18 = 18,36 ,45 ..., 90 = 18×5×6/2 = 270

Sum = 2550 + 594 - 270 = 2874