Question

What is the sum of the 28 numbers between 10 and 200 that divisible by 7?

Answer 1

Answer is 2954

since the no. b/w 10.......200 which are divisible by 7 are,

21+28+35+42+..........196

it forms an AP so that

a= 21
d=7

so the sum of 28 terms is given by

28/2 (42+169)

solve it **

Answer 2

The numbers between 10 & 20 that are divisible by 7 are 14,21,28,35,42,49,56,63,70,77,84,91,
98,105,112,119,126,133,140,147,154,161,168,175,182,189 and 196

So their sum is 2,835

Hope it helps