The first digit can be any one of 5 choices. For each of those, the second digit can be any one of 4 choices. For each of those, the third digit can be any one of 3 choices. So the total number of permutations without repetition is 5 x 4 x 3 = 60.
-58264
Forming three three digit numbers that use the numbers 1-9 without repeating, the highest product possible is 611,721,516. This is formed from the numbers 941, 852, and 763.
9876543210
9,876,543,210 9876543210
There are 25 such numbers.
256
24
18, if leading 0s are disallowed.
Without repeating digits (not digets!) and without leading 0s, 600 of them.
98765
60
468, 486, 648, 684, 846, 864.
86420
It is a repeating decimal.
-58264
4 x 3 x 2 ie 24
5040