I think this is how Gauss managed to sum the integers 1 to 100 in record time when he was a schoolboy as 1+2+....+100 is the same as 50*101.

## Gauss and the Handshake Problem

I think this is how Gauss managed to sum the integers 1 to 100 in record time when he was a schoolboy as 1+2+....+100 is the same as 50*101.