Within rules you can use the notation 0x10 (for hexadecimal), instead of the notation 16 (for decimal). Bome MIDI Translator will automatically do the conversion. The formulas work correctly right away, however after saving and re-opening a project file, the value you entered will show in decimal. I often put the hex value also in comments so later when I go back to it, I can remember the value.
For instance.
// 0x10
ga=0x10
Will send the value of ga to 16
Later it will show as
// 0x10
ga=16
Windows has a programmers calculator if you want to use it as well. Just use the 3 bars menu to change it to programmer mode.