How many different ways can 12 employees be assigned to 4 different jobs, if the 1st job needs 5 people, 2nd job needs 3 people, 3rd job needs 2 people and the 4th job needs 2 people.
if this is the case, the ACs would be as under:
where you have to multiply the numbers whose unit digit likely to be appeared as 0 or 5. here we have the following results:
= 12C5 * 7C3 * 4C2 * 2C2
the unit digit of the above multipication is 0. so we can figure out that the AC must have unit digit.....