A handheld calculator draws a steady 0.300 mA. How long does 1.00 C of charge take to pass through it?

1. Start from I = delta Q / delta t and rearrange to delta t = delta Q / I. 2. Convert the current to base units: 0.300 mA = 0.300 x 10^-3 C/s. 3. Substitute: delta t = 1.00 C / (0.300 x 10^-3 C/s). 4. That gives delta t = 3.33 x 10^3 s, which is slightly less than an hour. 5. 3.33 x 10^6 s is the trap of forgetting that milli means 10^-3 rather than 10^-6. _Source: OpenStax College Physics (CC BY 4.0), Ch 20 "Electric Current, Resistance, and Ohm's Law", section 20.1 Current_