Question

Find the sum of all natural number from 1 to 100

Answer 1

Sn =n/2(2a+(n-1)d)
n=100
a=1
d=1
so S100= 100/2(2(1)+(100-1)1)
= 50(2+99)
=50(101)
=5050

Answer 2

Answer:

5050

Step-by-step explanation:

Natural numbers from 1 to 100 = 1,2,3,....,100

Since it is an A.P.

So, first term = a = 1

Common difference =d = 2-1=3-2 =1

Formula of sum of first n terms = $S_n=\frac{n}{2}(2a+(n-1)d)$

Substitute n =100

So, $S_{100}=\frac{100}{2}(2(1)+(100-1)(1))$

$S_{100}=50(101)$

$S_{100}=5050$

Hence the sum of all natural number from 1 to 100 is 5050.