I spend far too much time flipping between calculator and sketch up. It would be much easier if you could enter simple calculations directly as measurements and scales from the keyboard. This would be very easy to implement. Suggest the equals operator is used to signify formula (as used in spreadsheets)
eg When scaling be able to enter = 4095/2242
This could be extended to allow some variables:
Eg Last use of tape-measure could be stored in variable called T.