13 is one of the primes from 10 - 20.....................there are 4 in that 10 number span.........the next two...........are 17 and 19.........which add to 36..............like the degrees in a circle........the start of it......




There are 360 degrees in a circle.............................3 + 6 + 0 = 9....................three 5's...................9/3 = 3............nine divided by 3 = 3................................3 is how pi starts out..........


square root(13) =

3.60555127546