Make fractions comprehensible.
Press the cursor button in the toolbar to control the tool. Use the '+' and '-' buttons to change the numerator or the denominator or select the part of the fraction in the figure you would like to change. The number and the visual fraction will change simultaneously. If you select the '+' next to the numerator while all components of the fraction are already coloured, a new pizza will appear to the right of the fraction. Click on the '-' next to the numerator and the new pizza disappears.
To hide the numerator and the denominator, select the eye icon to the left of the fraction. The numerator and the denominator become question marks. Click on the eye icon again to uncover the numerator and the denominator in the fraction.