This is a game for two players.
You will need a 100 square which you can download
here or you can
use the interactivity below.
The first player chooses a positive even number that is less
than $50$, and crosses it out on the grid.
The second player chooses a number to cross out. The number
must be a factor or multiple of the first number.
Players continue to take it in turns to cross out numbers, at
each stage choosing a number that is a factor or multiple of
the number just crossed out by the other player.
The first person who is
unable to cross out a number loses.
Here is an interactive version of the game in which you drag
the numbers from the left hand grid and drop them on the right
hand grid. Alternatively, click on a number in the left hand
grid and it will transport to the earliest empty location in
the right hand grid. You can rearrange the numbers in the right
hand grid by dragging and dropping them in position. The
integer in the top right hand corner grows with the number of
factors/multiples you have in a row.
This text is usually replaced by the Flash movie.
An extension to the game, or a suitable activity for just one
person, is suggested in the
Possible extension in the
Teachers' Notes