Sample = Total - Tare
if the uncertainties are given by normal distributions and are not correlated
Sample = Total - Tare
Sample = Total + Tare
A good way to measure electrical power: multiply the current and the voltage drop
Power=I*V
Power = I v
Power = Power [(I/I)2 + (v/v)2]1/2
Division works like multiplication. More complicated operations give very complex error propagation: a topic of ongoing research.