Question

The formula to find sum of first n positive integers

Answer 1

1 + 2 + 3

= 3 x (3+1)/2

= 3 x 4/2

= 12 /2.

=6

1+2+3+4 .

= 4 x (4 + 1)/2 ..

=4 x 5/2

=20/2

=10

From the examples you know that if we take sum of first three terms, the answer

is the product of 3 x (3+1)/2 = 3 x 4/2 =12=2=6

Similarly if you want to find the sum of first 4 terms, the answer is, the product of

4 x (4+1)/2 =4 x 5/2 =20/2/10

1+2+3+……..+ n = n (n+1)/2 [where n represents the number of terms]

this is the formula used to find the sum of the first n natural number