March 1, 2020

Sum up the first 1000 Positive Integers

You have under 20 seconds! No calculators allowed, of course.

 

1 + 2 + 3 + ... + 998 + 999 + 1000 = ?

*The ellipsis ( ... ) stands in for all the numbers in between 3 and 998 that are not shown.

What is the sum? (The goal is to find the sum in the most efficient way, i.e. fast)

500,000
500,500
450,000

Incorrect. 

Correct!

Incorrect.