Possible to design a circuit with EXACTLY 10mA of current?

[cutler]

Why isn't it possible to design a circuit with EXACTLY 10mA of current?

Also

When an ohmmeter is used to measure resistance in a series-parallel circuit, what precautions must be taken?

 

[vk6kro]

You could get 10 mA if you had exactly 10 volts across a 100% accurate 1000 ohm resistor.
However, you can't get an exact 10 volts because all voltage supplies have some error, and all resistors are not 100 % accurate either.

You have to be sure the resistance you are measuring is only due to the resistor you want to measure. Others in parallel with it will affect the reading.

 

[berkeman]

Why isn't it possible to design a circuit with EXACTLY 10mA of current?

Also

When an ohmmeter is used to measure resistance in a series-parallel circuit, what precautions must be taken?

So how about you give us your answers now, based on vk6kro's hints?