At some places, PCC2 accepts a prefix argument which modifies the following keystroke. Normally, this is used to set the amount you wish to build, move, etc.
To use a prefix argument, just start by typing a number. A yellow popup will appear. Keep typing, and confirm by pressing the key whose function you want to perform. For example, to build 15 factories on the Buildings screen, you'd type 15+.
- Backspace: Correct typos
- *: Multiply. Enter 3*3 for a prefix argument of 9
- /: Divide. Enter 20/4 for a prefix argument of 5
- ESC: Cancel prefix argument
Note that there is no addition or subtraction operator for the prefix argument. Instead, simply use the respective function multiple times. To build 10+15 factories, type 10+15+.