An old (probably false) story about Gauss tells how, at age 6, Gauss' schoolteacher wanted some peace and quiet, so he gave the class an exercise: add up the numbers 1 to 100. Naturally, he assumed this would take them a while.
Unfortunately, Gauss immediately reasoned as follows, and gave the right answer: pair off the biggest and smallest numbers, to get (1+100) + (2+99) + .... Now note that each pair adds up to 101, and that there are exactly 50 such pairs. So the sum is 5050.
The story how Gauss quickly added up the numbers 1 to 100 (100% fake story) is probably better, if even more groundless.
IMPORTANT WARNING! EVERYTHING BELOW THIS LINE WAS WRITTEN BY ME, BUT UNDER A SEPARATE TITLE. IT WAS MOVED BY SOME EDITOR (I USE THE TITLE GIVEN BY THE E2 GODS) AND DUMPED BELOW WHEN E DECIDED TO NUKE THE ORIGINAL. EVERYTHING2 BELIEVES IN YOU, YOUR WORDS, AND YOUR TITLES. EXCEPT WHEN IT DECIDES TO CHANGE SOMETHING. HAVE A NICE DAY.
Unlike the story of how Gauss quickly added up the numbers 1 to 100, which is only probably fake, this story was made up (I don't know whom by), so it is guaranteed 100% fake.
When Gauss was 6, his schoolmaster, who wanted some peace and quiet, asked the class to add up the numbers 1 to 100.
"Class," he said, coughing slightly, "I'm going to ask you to perform a prodigious feat of arithmetic. I'd like you all to add up all the numbers from 1 to 100, without making any errors."
"You!" he shouted, pointing at little Gauss, "How would you estimate your chances of succeeding at this task?"
"Fifty-fifty, sir," stammered little Gauss, "no more..."