Glen says, when someone picks a positive integer, and then writes down a sum of all integers from one to the integer that was picked and then adds all the integers back down to one, the
sum will be the square of the integer that was picked.
For example:
Pick 5, 1+2+3+4+5+4+3+2+1=52
Pick 7, 1+2+3+4+5+6+7+6+5+4+3+2+1=72
Will this always work for any positive integer?
Why?