24
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.
9
No 5291 is not a prime using 2 numbers. It is a prime using three numbers.
89,999 different numbers i guess
You can make twelve using three different numbers by adding 1, 4, and 7 together: 1 + 4 + 7 = 12. Another combination could be 2, 3, and 7: 2 + 3 + 7 = 12. You can also use 3, 4, and 5: 3 + 4 + 5 = 12.
1000
You have seven different digits (symbols) to choose from, so you can form seven different one digit numbers and 7×7=72=49 different two digit numbers.
1 x ((7 x 3) + 3) = 24
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.
9
No 5291 is not a prime using 2 numbers. It is a prime using three numbers.
89,999 different numbers i guess
There are 3*2*1 = 6 of them.
You can make twelve using three different numbers by adding 1, 4, and 7 together: 1 + 4 + 7 = 12. Another combination could be 2, 3, and 7: 2 + 3 + 7 = 12. You can also use 3, 4, and 5: 3 + 4 + 5 = 12.
6 possible 3 digit combonations
Using 1, 2, and 3, you can make 27 whole numbers.
Using the digits of 1345678, there are 210 three digit numbers in which no digit is repeated.