Question

Find the sum of first 1000 positive integer

Answer 1

Hi !

The positive integers form an ap :-

1,2,3,4 ....... 1000

a = 1
d = 1
l = 1000

l = a + (n-1)d
1000 = 1 + n - 1
n = 1000

sum = n/2[a + l]
        = 1000/2 [ 1 + 1000]
        = 500 x 1001
        = 500500

sum of  first 1000 positive integer = 500500

Answer 2

Positive integers = Natural numbers.

We know that Sum of first n natural numbers is n ( n+1)/2

Sum of first 1000 positive integers or natural numbers =1000*1000+1/2

=500*1001

=500500

therefore sum of first 1000 positive integer is 5,00,500