I'm having trouble with a computer algorithm. In my class I've learned how to solve something like this
The worst hockey team can choose a single player from 3 teams. each team has 20, 21, 24 players respectively. How many players are there to choose from
And something like this
How many license plates can be made which have 3 numbers and then 3 letters.
The problem I am having is with a question like this (which i found in my textbook, for extra work):
How many strings of 4 digit decimals (1.0000) are there which don't contain the same digit 3 times?
I'm not sure how to solve with the condition. Can someone offer help?