The answer is 3*3*2*1 = 18.
If the leading digit is 0 it is not a 4-digit number.
24
256
Without repeating digits (not digets!) and without leading 0s, 600 of them.
60
It is a repeating decimal.
24
256
18, if leading 0s are disallowed.
Without repeating digits (not digets!) and without leading 0s, 600 of them.
98765
60
-58264
468, 486, 648, 684, 846, 864.
86420
It is a repeating decimal.
4 x 3 x 2 ie 24
5040