CAD tip # 12777:

+ addition
- subtraction
* multiplication
/ division
^ power
() expression separator

ln(expr) - natural logarithm
log(expr) - decimal logarithm
sqrt(expr) - square root
cos(expr) - cosine
sin(expr) - sine
tan(expr) - tangent
acos(expr) - arc cosine
asin(expr) - arc sine
atan(expr) - arc tangent
exp(expr) - e^x
abs(expr) - absolute value
pi - pi (3.1415926536)
round(expr) - rounding to the nearest whole number
rounddown(expr) - nearest lower whole number
roundup(expr) - nearest higher whole number

IF(cond,iftrue,iffalse) - conditional expression
AND(expr) - and
OR(expr) - or
NOT(expr) - negation
< = >  - comparison
 example: =IF(OR(A=1,B=3),8,3)

You need to keep proper dimensional units in the expression results, e.g. log(100) * 1.0m.