Archive | Times Tables

How to See Why the Divisibility Trick for 3 Works

There’s a nifty trick for finding out if 3 divides evenly into a number. This little proof shows why the trick works.

Times Tables, Learning the Threes

Learning times tables can seem like drudgery. But here’s a fun, rhythmic game approach to learning the threes. Try it and see if you don’t have success.

Multiplication Trick #3 — Multiply by 25 FAST!

Here’s a great way to help students get two for the price of one.
First, they make connections between multiplication and a topic very dear to their hearts: money. That’s because the trick is for multiplying by 25, and in using this trick, you use the fact that four quarters make a dollar. Secondly, students who learn the trick gain even greater “number sense,” as they learn not just about multiplication, but also about divisibility, remainders, and the effect of remainders on the results of division. This trick is rich in concepts.

Multiplication Trick #2 — Multiply by 15 FAST!

Here’s a great trick that helps you quickly multiply by 15. It’s handy for many real life situations, such as when you need to calculate a 15% tip at a restaurant. It involves nothing more than simple math. Try it, and then watch as your friends and family gaze in amazement.