24, and the word is digit, not diget!
16
Without repeating, 4. With repeating, 8.
5040
Factorial 4 ie 4 x 3 x 2 x 1 = 24
24
93876
4p3*3p1 equal to 72 ways
Including leading zeroes, the answer is 720. If you don't include leading zeroes, then 600.
Without repeating digits (not digets!) and without leading 0s, 600 of them.
1 × (3 + 5 + 7 + 9 + 11 + 13 - 15 + 17) = 50.
4 x 3 x 2 ie 24
(987 + 13)(6 + 4) x 2 x 5 = 1000 x 10 x 10 = 100000