Question

What is the sum of the first100 positive integers?

Answer 1

50*101 = 5050

Answer 2

Why?

Answer 3

Please explain

Answer 4

To find the sum of the first 100 integers, you first add 1 plus 100 (the first and last numbers of the set) and get 101. Do the same with the next two integers, 2 and 99 and you'll get 101. Since you are adding two integers at a time and there are 100 integers between 1 and 100, you'll get 101, fifty times.
Therefore, a shortcut would be to simply multiply 101 times 50 and get 5,050.

Read more: http://wiki.answers.com/Q/What_is_the_sum_of_the_first_100_positive_integers#ixzz1vRdZF900

Answer 5

The sum of the first n natural numbers is given by n*(n+1)/2