Question

What is the sum of the first 60 positive integers?
(Points : 1)
60

61

1800

1830

Answer 1

@whpalmer4

Answer 2

first plus last, times the number of numbers, times 1/2.

Answer 3

This is about how Carl Friedrich Gauss did it when he was a little boy. (Don't worry, I couldn't have done this when I was a little boy either.)

1 + 2 + 3 + 4 + 5 + 6 + .... + 58 + 59 + 60
60 + 59 + 58 + 57 ... + 3 + 2 + 1

Notice that there are 60 numbers to be added. Now notice that each vertical pair adds to 61. So twice the required sum is 60 * 61. Therefore the sume of the first 60 numbers is 1/2 of 60 * 61.