## Multiple Bingo

There are many versions of bingo used to practice maths skills in the classroom. For example, Adrian Bruce’s Multiplication Bingo. Or play Matho 2 online. My version needs a twenty-sided die (icosahedron) and a 3 by 3 square grid.

Students draw up the grid and then write in nine different numbers from 2 to 100.

The die is rolled and the number called out. If a player has that number, or any multiples of it, then one of these numbers can be crossed off. The first player to finish one line and yell “BINGO” scores one point. The first player to cross out all nine numbers and yell “BINGO” scores a further two points.

It is interesting to note which numbers students write in their grids. What are the best numbers and where should they be placed? Shannon and Sharnie, two of my students, win this game more often than not!

Remember we are only using a 20 sided die, so we are looking at factors up to 20. We also exclude 1 since all numbers are multiples of one. Hence, although the number 84 has 12 factors <= 100 (1, 2,3,4,6,7,12,14,21,28,42,84), we can only use 7 of these in this game (2,3,4,6,7,12,14). Based on these rules, do you think my grid shown at right gives you the best chance of winning?