Math Probability
posted by katie on .
3) For years, ocean going ships have been using colored flags for signaling. By changing the order of the colored flags, the ships can send out different signals. If most ships carry six flags (each of different colors) how many different signals are possible if...
a) all six flags are used? b) four flags are used?
Please help, this is very confusing to me

all six are used :
number of ways = 6! = 720
four are used:
number of ways = 4! = 24