One coulomb of charge has the equivalent charge of 6.25x10^18 electrons. This is determined from the value of charge on one electron and the value of charge for 1 coulomb.
The algebraic solution is laid out by DronStudy as follows:
One electron has a charge equivalent of 1.6x10^-19 coulomb. This is written as 1.6x10^-19 C = 1 electron.
To get the value of 1 C, both sides of the equation have to be divided by 1.6x10^-19. This is written as 1 C = 1/1.6x10^-19 electrons. Dividing 1 by 1.6x10^-19 gives a value of 6.25x10^18 electrons per coulomb.
Given this value, the number of electrons passing through a circuit over a given time can be calculated. One ampere equals 1 coulomb per second. Therefore, a vacuum cleaner with a 3.5-amp motor uses 3.5 coulomb per second multiplied by 6.25x10^18 electrons/coulomb, or 21.875x10^18 electrons per second. That is 21,875,000,000,000,000,000 electrons every second!
This equivalency can also be used to determine the number of electrons required to do a given amount of work. Given that 1 volt equals 1 joule/coulomb, a circuit producing 18 joules of work off of a 9-volt power source would require 2 coulombs worth of charge, or 12.5x10^18 electrons.