Question

what's the sum of 1 to 100 natural numbers​

Answer 1

Let S be the required sum. Clearly, it is an Arithmetic Progression whose first term = 1, last term = 100 and number of terms = 100. Therefore, the sum of first 100 natural numbers is 5050.

Answer 2

Sum of the 1 to 100 numbers is

n(n+1)/2

100×(100+1)/2

100 ×101/2

50×101

5050