Write the following numbers on the board (or an overhead projector):
| 1 | 2 | 3 | 4 | 5 | 6 |
| 7 | 8 | 9 | 10 | 11 | 12 |
| 13 | 14 | 15 | 16 | 17 | 18 |
| 19 | 20 | 21 | 22 | 23 | 24 |
| 25 | 26 | 27 | 28 | 29 | 30 |
| 31 | 32 | 33 | 34 | 35 | 36 |
| 37 | 38 | 39 | 40 | 41 | 42 |
| 43 | 44 | 45 | 46 | 47 | 48 |
Split the class into two teams.
The object is to score the most points.
One team begins and selects a number.
That team gets that number of points,
but the opposing team gets all the proper factors of that number!
The number and its factors are erased or crossed out and cannot be used again.
Teams take turns selecting numbers until none are left.
then that team gets 38 points, and the opposing team gets 1 + 2 + 19 = 22 points.
If the second team selects 37, they would get 37 points added on to their 22 points,
but the first team would get nothing because the only proper factor of 47 is one and it has been erased.