8
Problems(2)
Consecutive numbers multiplication
Source: 239 2009 S8
7/29/2020
Alireza multiplied a billion consecutive natural numbers, and Matin multiplied two million consecutive natural numbers. Prove that these two got different results or one of them has made a mistake.
Christmas presents
Source: 239 2009 J8
7/29/2020
Each of the girls wants to mail each of the other a gift for Christmas. The packages contain no more than two gifts. If they have enough time, what is the smallest possible number of packages that they have to send?