An electron has a charge of -1.602*10^-19 C. If a piece of aluminum were given a positive charge of 1.6 micro coulombs electrons were removed from the aluminum during the charging process. Let the number of electrons removed be N.
1.6*10^-6 = N*1.602*10^-19
=> N = 1.6*10^-6*10^19/1.602
=> N = 10^13
Approximately 10^13 electrons have to be removed from a piece of aluminum during the charging process to give it a positive charge of 1.6 micro coulombs.