Question

find the sum of first 10 natural number​

Answer 1

1+2+3+4+5+6+7+8+9+10=55

Answer 2

Answer:

55

Step-by-step explanation:

We need to find 1+2+3+.....+10

This is an AP with

a = first term = 1

d = common difference = 1

n = number of terms = 10

We know that

Sn = (n/2)[2a + (n-1)d]

where Sn = sum of first n terms

In our AP, let X be the sum of first 10 terms

Hence,

X = (10/2)*[2*1 + (10-1)*1]

  =  (10/2)[2 + 9]

  = (10*11)/2

  = 55

Sum of first 10 natural numbers = 55

It is useful to know that:

Sum of first "n" natural numbers = n(n+1)/2