Question

find the sum of all natural no. bw 100 and200 which are divisible by 7.​

Answer 1

Answer:

2107

Step-by-step explanation:

Identify the smallest number between 100 and 200 that is divisible by 7.

Estimate = 100 ÷ 7 = 14.28 ≈ 15 (round up)

Smallest number = 15 x 7 = 105

Identify the biggest number between 100 and 200 that is divisible by 7.

Estimate = 200 ÷ 7 = 28.57 ≈ 28 (round down)

Biggest number = 28 x 7 = 196

Find the number of terms between 100 and 200 that are divisible by 7.

Tn = a1 + (n - 1)d

196 = 105 + (n - 1)7

196 = 105 - 7n - 7

196 = 98 - 7n

7n = 98

n = 14

Find the sum of all the natural number between 100 and 200 that are divisible by 7.

Sn = n/2(a1 + an)

s14 = 14/2 (105 + 196)

s14 = 2107

Answer: 2107