smallest=1234 greatest=4321
32 -(1+4) =27
1234 billion
There are 4 ways to chose the first digit. Then because there is to be no repetition, there are 3 ways to choose the second. This means that there are 4 x 3 ways of setting down the first two digits 12 _ _ 13 _ _ 14 _ _ 21 _ _ 23 _ _ 24 _ _ 31 _ _ 32 _ _ 34 _ _ 41 _ _ 42 _ _ 43 _ _ .... now you can take it from there.
a 8-digits palindromic number is a number consisting of a 4-digits number written and then written backward, i.e. 1234 4321 so there are as many palindromic 8-digits numbers as 4-digits numbers so from 1000 to 9999, so there are 8999 palindromic 8 digits number (I assumed that 00011000 is not to be considered as a valid 8 digit number)
4*3*2*1 = 24
64 if repetition is allowed.24 if repetition is not allowed.
256
That would be 4! = 4 * 3 * 2 * 1 = 24
24
Twelve of them.
4 x 3 x 2 ie 24
1234
With repeats: 4×4 = 16; Without repeats: 4×3 = 12.
1234, 2637, 7777, 2727 are examples of a four digit number. So any random four numbers are four digits.
smallest=1234 greatest=4321
4*3*2*1 = 24. The actual numbers are 1234 1243 1342 1324 1423 1432 2134 2143 2314 2314 2413 2431 3124 3142 3234 3243 3413 3431 4321 4312 4213 4231 4123 4132