The tool opens to show a 1-100 number square. You can hide the numbers either by clicking the arrows on the left and bottom edges, or by clicking on individual numbers. Click again to show hidden numbers.

The ‘Hide all’ button hides all the numbers with one click, and clicking the ‘Show all’ button shows them all.

Click the ‘Colour square’ button at the bottom left to change from showing/hiding numbers. When this is selected, clicking on the arrows or on individual square will cause rows or columns or individual squares to be highlighted in a colour. Click again to remove the colour. The ‘Clear colours’ button becomes available once some squares are coloured: this removes all colouring with one click.

You can change the colour by clicking the colour picker next to the ‘Colour’ button.

Clicking ‘Set up’ opens a menu in which you can alter the number of rows or columns, or the start number.

Clicking Reset undoes any changes you have made, returning the tool to its default state.