Math Genius - Divisibility Rules lyrics

Divisibility by 1 Any number, when divided by 1, is still itself. It doesn't change. That means all whole numbers are divisible by 1. That was easy! Divisibility by 2, 4, and 8 All even numbers (and only even numbers) are divisible by 2. Check if a number ends in 0, 2, 4, 6, or 8 -- if it does, it's an even number, and it's even and divisible by 2. Divisibility by 3, 6, and 9 Divisibility by 3 has the coolest rule. It turns out that for every number that's divisible by 3, if you add up all the digits (and keep adding digits until you have a single digit), the result always equals 3, 6, or 9. Divisibility by 5 and 10 A number is divisible by 5 if it ends in 0 or 5. It's that simple. A number is divisible by 10 if it ends in 0. Even simpler! Divisibility by 7 There's no easy trick to figure out whether something is divisible by 7. Sorry. Divisibility by 11 The divisibility rule for 11 is a bit complicated, and the simplest way involves a slight tweak on the divisibility rule of 3, using the number's digit sum. More Thoughts About Divisibility>