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

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- Mar 22nd 2009, 12:38 PMJassimSumming 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?

- Mar 22nd 2009, 01:00 PMrunning-gag
You can use Gauss method

$\displaystyle S=1 + 2 + 3 + \cdots + 98 + 99 + 100$

$\displaystyle S=100 + 99 + 98 + \cdots + 3 + 2 + 1$

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

2S is the sum of 100 terms equal to 101

Therefore $\displaystyle S=\frac{100\cdot101}{2}=5050$ - Mar 22nd 2009, 01:41 PMJassimthx
thanks very much for your help

- Mar 23rd 2009, 05:21 AMstapel
See also

**this thread**.

(Wink)