There are 720 of them!
90
im not geeky enough to answer that
The number of possible 3 digit combinations you can make out of 1-9 with outrepeated digits is:9C3 = 9!/(3!(9-3)!) = 84
Not sure what a "didget" is. It is possible to make 18 5-digit numbers.
You can make 24 4-digit numbers. 1111 2222 3333 4444 5555 6666 1234 2345 3456 1356 6543 5432 4321 1432 ok i give up!
There are many combinations possible The most popular combination is 2,3,5,17,23.
There are 5*4*3*2 = 120 such numbers.
0000, 0009, 0090, 0099, 0900, 0909, 0990, 0999, 9000, 9009, 9090, 9099, 9900, 9909, 9990, 9999
You can make 5 combinations of 1 number, 10 combinations of 2 numbers, 10 combinations of 3 numbers, 5 combinations of 4 numbers, and 1 combinations of 5 number. 31 in all.
9999999999 100000000
Just one. In a combination, the order of the digits does not matter.