I was interested to hear recently a little tale about German mathematician, astronomer, and physicist Johann Carl Friedrich Gauss (1777 - 1855).
When he was at junior school the teacher (obviously requiring an hour or two's respite) asked the class to sit and add up all the numbers from 1 to 100. 1 +2 +3 + 4 etc.
He was mortified to glance up and see young Gauss with his hand aloft 25 seconds later to declare that he'd finished and the answer was 5,050.
Gauss's mathematical brain had spotted a pattern in the task that meant the answer could be determined by a single multiplication rather than 100 additions.
I'd be interested to know if anyone can spot the short-cut without referring to Mr Google. The answer will be shown in the first comment so it's not a competition.
So just settle down with your excercise books and keep quiet at the back there.....