Learning in a row.
Below you choose the row you want to practice. With the eraser you erase, so you can start again. The button with the ear turns the sound on or off. The upper numbers are like a calculator, because with them you can enter the answer. For that click on the button with the thumb. The colors at the top right are to write the numbers in a different color.
If you only want to see the numbers, do not want enter them yourself, then you can click on the button with the eye. So you can learn faster.