Discussion Forum



1)

The sum of first 45 natural numbers is :


A) 1035

B) 1280

C) 2070

D) 2140

Answer:

Option A

Explanation:

Let Sn =(1 + 2 + 3 + ... + 45). This is an A.P. in which a =1, d =1, n = 45.

$S_{n}= \frac{n(n+1)}{2}=\frac{45(45+1)}{2}$

=1035