There are 27 of them.
234, 243, 324, 342, 423, and 432.
If you can repeat a digit, there are 27. If you can't repeat a digit, there are only 6.
012345 or -543210, if negative numbers are permitted.
972.
Using the digits of 1345678, there are 210 three digit numbers in which no digit is repeated.
You can select 9 numbers for the first digit, 8 numbers for the second digit, and 7numbers for the third digit; so 504 (e.g. 9*8*7) different three digit numbers can be written using the digits 1 through 9.
six
Using division or multiplication or addition??
it would be 0000.01
81 As there are no limits stated then you can have a number comprising a repeated single digit (such as 2222), two pairs of numbers (e.g. 2244) or three different numbers (such as 2462). The first digit can be one of any of the 3 numbers. The second digit can be one of any of the three numbers, as can the third digit and also the fourth. Then you can have 3 x 3 x 3 x 3 = 81 different 4-digit numbers using the three given numbers.
Using prime factorization, there are 2 three digit numbers with 9 factors: 512 and 768. There are no three digit numbers with 10 or more prime factors. 512=2^9 and 768=3*2^8
6 possible 3 digit combonations
48 of them if digits may not be repeated. 100 if they can.
24 three digit numbers if repetition of digits is not allowed. 4P3 = 24.If repetition of digits is allowed then we have:For 3 repetitions, 4 three digit numbers.For 2 repetitions, 36 three digit numbers.So we have a total of 64 three digit numbers if repetition of digits is allowed.
10
100122 or, if negative numbers are permitted, -998877