Gauss is a famous great scientist in Germany. His most famous story is that when he was 10, the primary school teacher gave an arithmetic problem: calculation 1+2+3+...+ 100 =?

This stumbles the children who have just learned mathematics. They added up the figures one by one according to the requirements of the topic. But at this moment, there came Gauss's voice: "Teacher, I have calculated it!" " "

The teacher was very surprised. Gauss explanation: because1+100 =10, 2+99 =10/kloc-0, 3+98 =10/kloc-.