Maths game - Multiplication 4 in a row

In this game we use a multiplication grid and a different colour pen for each player, to play 4 in a row. Each player fills in a square on the grid, with the aim of getting 4 numbers in a row, horizontally, vertically or diagonally.
The aim is to get as many lines of 4 in a row as you can, whilst trying to stop the other player from getting lines of 4.