### Divisibility Rule for Seven (TANTON Mathematics)

Many folk know divisibility rules for 3, for 5, for 9, for 11 and so on, but what about a divisibility rule for the number 7. There is one, and here it is! (Plus, you'll learn from this how to create your own divisibility rules for 13, and 17, and 43, and 97 and the like!)

Length:
06:00