367 ,376 ,396, 369, 379, 397, 637 ,673 ,693, 639, 697, 679 ,763, 736, 769, 796, 793, 739, 976, 967 ,937 ,973, 976, 967 so its twenty-four unless you can use the numbers more than once in each three digit number.
ten factorial = 10! = 3,628,800
27 three digit numbers from the digits 3, 5, 7 including repetitions.
24
24
128
9999
100,000
12
512
24
There are 504 such numbers.
There are 60480 numbers.
840
823543
6
There are 5! = 120 such numbers.
There are 7,290 different 4-digit numbers that can be formed from the digits 1-9 without repetition.