Question

what is the sum of natural numbers from 11 to 40​

Answer 1

Step-by-step explanation:

The sum of all natural numbers from 11 to 40, is the same as

(sum of natural numbers from 1 to 40) - (sum of natural numbers from 1 to 10).

Sum of natural numbers from 1 to n can be denoted by (n).(n+1)/2.

So sum of natural numbers from 1 to 40 would be (40)x(40+1)/2 = 40x41/2 = 820.

Answer 2

Answer:

765

Step-by-step explanation:

let A1 = 11

An= 40

d= 1

an = A1 + (n-1)d

40 = 11+ (n-1)1

29. = n-1

n = 30

sn = n/2 (A1 + An)

sn = 30/2(11+40)

sn = 15(51)

sn = 765