104 = 10000 if digits can be repeated, 5040 if not.
The above answers assume a code can start with a 0. If not,
9000 if digits can be repeated and 4536 if not.
45
9876
There are 24.
I assume you mean how many 4-digit numbers can be made from a set such as {A,A, B, C} where A, B and C are single digits. There are 12 such numbers.
3*3*2*1 = 18
If the numbers are not repeated then the highest 5 digit even number to be made out of 0123456789 is : 98764.
94
45
How many license plates can be made using either two uppercase English letters followed by four digits or two digits followed by four uppercase English letters?
9876
10
There are 24.
I assume you mean how many 4-digit numbers can be made from a set such as {A,A, B, C} where A, B and C are single digits. There are 12 such numbers.
3*3*2*1 = 18
15 digits (the first four digits is the branch code)
If you're asking for 4 digit numbers where all four digits are odd, then the lowest number possible is 1111, and the highest is 9999. You only have 5 digits to work with. The answer is: 54 - 53 = 625 - 125 = 500.Subtract the 5 cubed for the numbers less than 1111, which are not four digits.
If the digits may be repeated, there are four choices for the first digit, four choices for the second, and four choices for the third. Thus there are 4x4x4 = 64 possible three-digit numbers with those digits. If the digits may not be repeated, there are still four choices for the first digit, but then only three remaining choices for the second, and then just two choices for the third. In this case there are only 4x3x2 = 24 possibilities.