A current is not a substance. It is a rate — the rate at which charge crosses a section of conductor — and once you hold that, $Q = I t$ stops being a formula to memorise and becomes a definition to read.

Read aloud: Q equals I t. $Q$ is the charge that has passed, in coulombs; $I$ is the steady current, in amperes; $t$ is the duration of the flow, in seconds. Solve it for the charge going forward, for $I = \dfrac{Q}{t}$ when the charge and the clock are known, or for $t = \dfrac{Q}{I}$ when you are asking how long a process must run. Note the steadiness clause: if the current varies, this relation gives you the AVERAGE, and the honest version needs calculus.

Now the trap this lesson exists for. Batteries are not rated in coulombs; they are rated in milliamp-hours or amp-hours, because that is what a user understands. An amp-hour is $Q = I t$ with the clock in hours, so converting it back to coulombs costs you two multiplications and not one: $\times 10^{-3}$ to turn milliamps into amps, then $\times 3600$ to turn hours into seconds. A 2000 mA·h cell is 2 A·h, and 2 A·h is 7200 C. Students who pay one of those two tolls and not the other land a thousand times or 3600 times off, and the answer still looks like a number.