The tool opens to show one function machine. Enter a number in the flashing input box on the left, then click ‘Go’ for the number to be processed by the machine. The input and output are recorded in the data table.

The function machine has arrow buttons. Those on the left change the operator (cycling though plus, minus, multiply and divide). Those on the right change the number (clicking the up arrow cycles through the series 1,2,3,4,...9,10,20,30,40...100, then back to 1; clicking the down arrow cycles through these values in the other direction).

By default, the function is displayed. There are two ‘Hide’ buttons on the function machine. Click these to hide the operator or the number, or both.

Buttons at the bottom left of the screen let you choose between ‘One machine’ and ‘Two machines’. When there are two, the second machine processes the output of the first.

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