Why comes the zero in the end, when we divide 201 by 20?
What means to divide 201 by 20? This has (at least) two different meaning. One is to divide integer, finding an integer quotient and an integer remainder, between zero and 19, which are unique and satisfy: 201 = 10\cdot 20 + 1. The reason why the quotient (10) ends in zero is that the greatest integer less than or equal to 201 which is a multiple of 20 is 200, ans 200 is 20 times a multiple of 10 (in particular 10), making the quotient a multiple of 10. The other common meaning of the division, is to find the unique real quotient satisfying 201 = 20 q, which exists and is unique because 20\neq . In this case, q = 10.05, which is not integer.