"When Carl Friedrich Gauss, the famous German mathematician and physicist was in elementary school (around 1784), his class was assigned the “busy work” task of adding all the numbers from 1 to 100 (1+2+3+4, and so on). This usually kept the class quiet for half an hour or so. Seven year-old Carl was sitting quietly with the correct answer (5050) while the rest of the class was just starting, so the surprised teacher asked him how he came up with the solution. He replied that he added 1 and 100 and got 101. Then he added 2 and 99, and got 101, 3 plus 98 = 101, and so on. He realized there was a pattern of 50 pairs of numbers with each pair adding up to 101. And 50 x 101 = 5050."

— i_think_therefore_i_