If it alternates and you start with a letter, then there are 11,232,000 permutations. Then if you start with a number and alternate, there are another 11,232,000 permutations, for a total of 22,464,000 permutations.
If you exclude the letters I, S, B, and O (because they look kind-of like 1, 5, 8, & 0 - kind-of important on license plates) then you are down to 6,652,800 & 13,305,600 respectively.
It is 720.
Only 5 ways: one each with one of the letters missing.
The largest 4 digit number with repetition is 9999. The smallest 3 digit number without repetition is 102 9999 - 102 = 9897
Largest 4 digit number with repetition is 9999 Largest 3 digit number without repetition is 987 Difference is 9999 - 987 = 9012.
9876-102 9704
uncopyrightable
It is 720.
9999
8889
The applicable term is assonance, which often creates rhymes.
9774
Only 5 ways: one each with one of the letters missing.
9876 - 123= 9753
The largest 4 digit number with repetition is 9999. The smallest 3 digit number without repetition is 102 9999 - 102 = 9897
Largest 4 digit number with repetition is 9999 Largest 3 digit number without repetition is 987 Difference is 9999 - 987 = 9012.
9876-102 9704
8888