10!/5!
= 30,240 ways
===========
pizza
Assuming all 45 digits are different (which they will not be if they are ordinary integers), then 456, if repetitions are allowed. That is 8303765625. If repetitions are not allowed then the number falls to 45*44*43*42*41*40 = 5864443200
There are 5 numbers of 1 digit, 25 numbers of 2 digits, and 75 numbers of 3 digits. This makes 105 numbers in all.
Six hundred.
504
pizza
543210
Assuming all 45 digits are different (which they will not be if they are ordinary integers), then 456, if repetitions are allowed. That is 8303765625. If repetitions are not allowed then the number falls to 45*44*43*42*41*40 = 5864443200
2,401
There are 5 numbers of 1 digit, 25 numbers of 2 digits, and 75 numbers of 3 digits. This makes 105 numbers in all.
5^4
10,000
Six hundred.
27 three digit numbers from the digits 3, 5, 7 including repetitions.
504
If repetition is allowed . . . . . 343 If repetition is not allowed . . . . . 210
Assuming leading zeros are not permitted, then: If repeats are not allowed there are 30 possible numbers. If repeats are allowed there are 60 possible numbers.