A 5 V potential difference across one ideal 220 Ω resistance produces a repeating decimal current. Exact rational arithmetic prevents the displayed rounded current from contaminating the power result.
Calculate current exactly
I=V/R=5/220 A=1/44 A. In milliamps this is exactly 250/11 mA, displayed as approximately 22.727273 mA.
Calculate power from unrounded values
P=V²/R=25/220 W=5/44 W. That equals exactly 1250/11 mW, displayed as approximately 113.636364 mW. The calculator does not multiply 5 V by a previously rounded 22.727273 mA string.
Use prefixes only for readability
The normalized results remain 1/44 A and 5/44 W. Choosing mA and mW changes their display scale by exactly 1000; it does not change the physical quantities or the calculation.
Do not infer a resistor rating
113.636 mW is the ideal operating-point dissipation, not a component recommendation. Tolerance, ambient temperature, derating, maximum voltage, duty cycle, and transient conditions remain separate engineering checks.