## If you add up the numbers 1-100 consecutively (1+2+3+4+5 etc) the total is 5050.

**If you add up the numbers 1-100 consecutively (1+2+3+4+5 etc) the total is 5050.**

- When you have got numbers listed consecutively, then the simplest way to find the sum is:
n * (n + 1) / 2

So, when n = 100, the sum would be:

100 * 101/2 = 5050

You can modify this method to find the sum of all numbers from 31 to 50!! Try it and let us know what you get!!

- 1 + 100 is 101

2 + 99 is 101

3 + 98 is 101Since there are 100 numbers (or 50 combinations) which total 101 as you proceed inward from 1 to 100, just multiply 101 by 50 and you come out with the answer 5050.