# Thread: Summing numbers 0 to 100

1. ## Summing numbers 0 to 100

Suppose you have a list of numbers from zero to one hundred. How quickly can you add them all up without using a calculator?

2. You can use Gauss method
$S=1 + 2 + 3 + \cdots + 98 + 99 + 100$
$S=100 + 99 + 98 + \cdots + 3 + 2 + 1$

$2S=101 + 101 + 101 + \cdots + 101 + 101 + 101$

2S is the sum of 100 terms equal to 101

Therefore $S=\frac{100\cdot101}{2}=5050$

3. ## thx

thanks very much for your help