Draw a number line on a piece of paper, marked from 0 to 20, like this:
(You could print off this sheet which has several number lines drawn on it.)
This challenge is a game for two players.The first player chooses two numbers in this grid and either $\times$ or $\div$.
He or she then marks the answer to the calculation on the number line.The second player then chooses two numbers and either $\times$ or $\div$, and marks that number in a different colour on the number line.
If the answer is too big or too small to be marked on the number line, the player misses a go.
The winner is the player to get four marks in a row with none of their opponent's marks in between.
What good ways do you have of winning the game?
Does it matter if you go first or second?
[This game is adapted from a SMILE Centre card.]