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