How many 4-digit codes can be created if no number can be repeated?

If you consider each set of 4 digits as a unique code regardless of numeric order (the code 0123 would be counted as a different code than 0132, 0213, 0231, 0312, 0321, 1023, 1032, 1203, 1230, 1230, etc.), there are 3,528 possible codes in the base 10 system containing the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.