Answer:
The mistake here is that resistance readings should be taken before connecting the power.
When you connect the power, the circuit becomes active and there is a current and voltage across the resistor.
So when you connect the multimeter, it gets a wrong reading as the current through the resistor is not the same as the current sent through it by the multimeter.
Also, since the resistor was connected to the circuit, the effective resistance between the 2 ports was measured. There could be many components in the circuit that affected this reading. So always pick up one end of the resistor from the circuit before measuring its resistance.
Step-by-step explanation: