How many even numbers less than 30,000 can be formed using only the digits 1,2,3, and 4?
I do not know why 2*4*4*4*2 = 256 is wrong.
- DixonLv 71 month ago
I assume it's wrong because we don't write leading zeros thus we need to include numbers like 3112, 32, 2 etc. So your approach is fine for 5 digit numbers and I think the easiest way is do 4, 3, 2 and 1 digit numbers as separate calculations and then add them up.