Digit Sum Divisors
Consider a natural number N and the sum of its digits S. Let’s call a divisor of S a Digit Sum Divisor of N.
Number Bases
The standard number system we use today is called decimal numbers, or base 10, meaning at every digit, we count to 9 before carrying one to the next smallest digit.
Chicken and Egg
Separating egg-laying chickens from non-egg-laying chickens by keeping them in boxes.