brian, i am actually using my pocket calculator for every math operation i do.
if the result is wrong, i check out the correction factor.
if i have to manipulate values with units i use a python script, as in my latest build one cannot multiply values with units and plain numbers. 10m * 5 = error message.
to avoid that i created python nodes that automatically convert to double and do the math. and multiply / divide with a factor that is an extra parameter to the node