Not if you use floating point maths, surely if you are mixing colours it could not be in whole kg/ltres etc. you convert the percent to a float then do the maths in floating point format, if required convert them back for the amount but 0.5 or some other fraction would mean you are not getting the correct shade.
How to i get 0.6 it is rounded to 1 and results are wrong
Do i use FLOATING DIV16 OR NORMAL DIV32 or DEDIV OR DEDIVR