Happy Number

math

Definition

Happy Number

A happy number (in base 10) is a positive integer that eventually reaches $1$ when you repeatedly replace the number by the sum of the squares of its digits.

Example: $19\to 1^2+9^2=82\to 8^2+2^2\to 68\to 6^2+8^2=100\to 1^2+0^2+0^2=1$.