#7
Aside:

A milliampere (mA) is a rate of electrical current flow through one specific crossectional point in a wire.

One ampere (A) is equal to one one Coulomb of electrons passing through the wire per second. (One Coulomb of electrons is equal to approximately 6.2415e18 electrons.)

One milliampere (mA) is equal to one thousandth of of an ampere, or one thousandth of one Coulomb of electrons passing through the wire per second -- approximately 6.2415e15 electrons.

If you have a 4 milliampere flow, then you have 4 thousandths of a Coulomb of electrons passing through the wire each second. If that flow is sustained for 1 hour (3600 seconds), then a total 14.4 Coulombs of electrons have passed through the wire -- or approximately 89.878e18 electrons.

Milliampere-hour (mAH) is a convenient shorthand way of expressing the total number of electrons that have flowed over time, and it is expressed as the product of the rate of flow in mA, multiplied by the duration of time in hours. Since we're multiplying a flow in units per second (mA), by a duration in hours, the resulting expression has been somewhat abstracted away from the original physical meaning behind the elementary units, and it would need further conversion if you wanted to get back to the elementary units. But it happens to be a convenient way of calculating electrical consumption in a lot of real-world scenarios without having to carry around too many superfluous digits of precision. (Nobody talks about their battery's stored energy capacity in terms of Coulombs.)