You can now for addition and subtraction but not for multiply and divide.
There is already a number in you tracker so all you have to do is move you mouse so the initial number is correct as your starting point, TAB to the figure you want to change if it is not the BOLD figure, then type what you want to add or subtract and then press + or -.
If you are finished then press enter or keep adding and subtracting to any of the figures by selecting it then typing a number with + or - after it.
The trick is you place the + or - after the figure you want to add or subtract and the number currently in your tracker is the base figure for the calculation.
One of the forum moderators. Versions 6.5 to 25 Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10 Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10