Question

Find the sum of all natural numbers between 10 and 200 which are divisible by 7

Answer 1

a = 14

d = 7

L = 196

=> a + (n-1) d =196

=> 14 +(n-1) (7) = 196

=> (n-1) (7) = 182

=> n - 1 = 26

=> n = 27

Sn = n/2 ( a + L)

= 27/2 ( 14 +196)

= 27 × 210 /2

= 27 × 105

= 2835

Answer 2

Your answer ⬇

____________________________

Given a = 14

d = 7

an = 196

a + ( n - 1 ) d = 169

14 + ( n - 1 ) 7 = 169

( n - 1 ) 7 = 182

n - 1 = 26

n = 26 + 1

n = 27

Sum = n / 2 ( a + an )

27 / 2 ( 14 + 196 )

27 ( 105 )

2835

_____________________________