This ITP has been remade so that it will work in modern browsers. It will remain free to use.

This ITP generates a 100 square. Choose a colour or the grey mask. You can then click on individual cells to hide or highlight them in different colours, and by clicking on the box at the left-hand foot of the grid and using the pointers you can hide or highlight rows and columns. The prime numbers and multiples can also be highlighted.
You can change the number of columns from 3 up to 13, the starting number, and its position – either top left corner or bottom left corner of the grid. Choose the mask option to create a temple that can be moved around the grid to hide or highlight particular groups of cells. The template can be rotated using the single arrow button.
The ITP can be used to explore different multiples, number sequences and patterns on grids of different sizes. The superimposed masked template can provide practice at adding groups of numbers and enable children to hypotheses about the sums and difference of the numbers.
The ITP can develop children’s ability to predict and generalise. Changing the number of columns provides a new grid to test general statements about the relationships between numbers and to look for counter examples.

For more addition and subtraction resources click here.