loop#

1 (i=1)

sum = 0 + 1 = 1
pro = 1 +* 1 = 1


2 (i=2)

sum = 1 + 2 = 3
pro = 1 * 2 = 2

3 (i=3)

sum = 3 + 3 = 6
pro = 2 * 3 = 6