Find the sum of first 100 natural numbers.

Let a be the first term and d be a common difference.

First-term a = 1. Common difference d = 1 Last term l = 100.

We know that sum of n terms o

= n/2(a + l) s100

= 100/2(1 + 100)

= 50(101)

= 5050.

Therefore, the sum of first 100 natural numbers = 5050.