Current consumption in milliseconds
40 milliseconds is 0.04/3600 hours = 1.1111e-5 hours therefore you have used 1.1111e-4 mAh.

= 0.0001111 mAh

Please note that you haven't used x amount of milli-amps per hour. You have used 10mA for 1.1111e-5 hours - the two numbers multiply

An ampere-hour is a unit of charge