When did Carl Friedrich Gauss invent the arithmetic progression?

Answer 1

Actually he did not invent arithmetic progression, but he had this insight as a 7 years old young student. When his teacher asked the class to sum all numbers from 1 to 100, the young Gauss did not need more than a few seconds to write "5050" in his slate. he noticed that 1+100=101, 2+99=101, 3+98=101, ... formed a sequence of 50 pairs that could summarize the calculation to 50x101= 5050.

Gauss is today considered by many as the greatest mathematician that ever lived.