Question

find the
sum of first 40 natural numbers

Answer 1

formula for sum of first n natural numbers is (n×(n+1))÷2
here n =40 so sum is 820

Answer 2

First 40 natural numbers:
1,2,3 .........40.

Sum of n natural numbers.
Sn =  [ n ( n + 1 )/ 2 ]
here,
n = 40

S40 = [ 40 ( 40 + 1 )/ 2 ]
= 20 × 41
= 820