jmc

There are 10 possibilities for the first digit. After the first digit has been chosen, there are 9 possibilities for the second digit. After these two digits have been chosen, there are 8 possibilities for the third digit and after the first three digits have been chosen there are 7 possibilities for the last digit. The total number of possible settings is $10\cdot 9\cdot 8\cdot 7=\boxed{5040}$.