Let n be a positive integer. Let R be the remainder when n2 is divided by n. How many different values can R take on?
Check this out:
https://gmatclub.com/forum/if-n-is-a-positive-integer-and-r-is-the-remainder-when-n-2-1-is-126395.html
There is no remainder.
n2n=n thus it will give you the positive integer you started with.
+537 
