# Can you make practising the times tables fun? Yes, just give me three dice…

As I was surfing through the blogosphere last week I stumbled upon a fantastic blog post explaining a fun game that you can encourage the pupils to play to practice their times tables. The inventor of the game is Dan Finkel, the author of the fantastic math for love blog. You can view Dan’s original post here.

I have summarised the game which is called Damult Dice below:

The Rules: Each player takes turns rolling 3 dice. First to break 200 (or 500, etc.) wins. On your turn, you get to choose two dice to add together, then you multiply the sum by the final die. That’s your score for that turn.

Simple; no bells, no whistles. For example, I roll a 3, a 4, and a 6 on my turn. I could either do (3+4) times 6 for 42 points, OR (3+6) times 4 for 36 points, OR (4+6) times 3 for 30 points. I’ll take the 42 points.

I spent some time playing this with kids the other day and I saw that (1) it was genuinely fun, and (2) it gives you almost all the multiplication practice you could ask for. In fact, it gives even more, because the choice of which dice to add and which to multiply reveals some interesting structure of numbers. Seriously, get a kid hooked on this game, and it’s the equivalent of dozens or hundreds of times table practice sheets.

I look forward to trying this one out soon!

Great, simple idea. Pity in Ireland we don’t do 11 and 12 tummies tables anymore

Great game. For ideas on using dice for math instruction of young children, visit the Rhombus Club’s Rhombus Room!

Looks great! Thanks for the find.

looks great think i should play on it with the students at school

Fun activity idea. And it has a calculus connection that can be discovered without invoking calculus at all.

Extension question for students: How can you get the largest possible product from any roll of 3 dice? Without trying this yet on students, I suspect they can discover some rules from gathering data. It won’t be obvious and they’ll need to make some hypotheses to test. Good!

Calculus insight: Given two real numbers, x & y, that have some fixed sum, S. What is the largest possible value of the product x*y? If you remember differential calculus, prove this for yourself, but the answer is that x*y is maximized when x=y.

Connecting to this problem: Obviously the numbers on any roll of 3 dice is fixed, so my calculus problem applies. When I saw the 3, 4, 6 dice roll, I knew I needed to multiply two numbers who were as close as possible to being equal. It didn’t take much thought to realize 3+4 & 6 would fit that bill, making the largest product of 42 without having to try any other possibilities.

Teaching idea: Obviously, elementary children won’t understand calculus, but they could still compute all possible products and pick the largest one as noted in the initial post. As a later exploration, students can be asked to discover rules to maximize their products. Don’t just play a game. Strategize! Encourage students not to just play, but to play well. I’d love to see what students discover.