Perfect Number in Java Programming Language

What is Perfect number ? 123 is the perfect number, why? Any number their first separate digit and than digits summation and multiplication, both are same than that number is perfect number other wise not perfect number. For example : 123 their digits sum=1+2+3=6 and mul=1*2*3=6 both are same, so we can say that 123 number is perfect number and 124 their digits sum=1+2+4=7 and mul=1*2*4=8 so we can say that 124 number is not perfect number. In this video lecture cover the perfect number or not using while loop and if else decision statement and also trace this program line by line using Watch and Output Window. How to set the Watch window also explain step by step.