#KnowledgeBit: In number theory, a #Happy #Number is a number which eventually reaches 1 when replaced by the sum of the square of each digit.
For instance, 13 is a happy number because 1^2+3^2=10, and 1^2+0^2=1. So is 19 (check it out) - but not 4.
knowledgezone.co.in/kbits/64089d...