Find the sum (41 + 42 + 43 + …. + 100).

It is required to find the sum (41 + 42 + 43 + …. + 100).

(41 + 42 + 43 + …. + 100) = Sum of integers starting from 1 to 100 – Sum of integers starting from 1 to 40.

Note:

Sum of first n natural numbers, 1 + 2 +3+…n,

From the above identities,

So, Sum of integers starting from 1 to 100

So, Sum of integers starting from 1 to 40

(41 + 42 + 43 + …. + 100) = Sum of integers starting from 1 to 100 – Sum of integers starting from 1 to 40.

(41 + 42 + 43 + …. + 100) = 5050 – 820 = 4230