Answer:
If repetition of digits is allowed, there are 10,000 possible passcodes.
Explanation:
We have 4 tasks - we have to find a number for each digit. We can only have numbers below 10 for each digit, since we can't have a number with two digits in one space.
Possibilities for first space : 10 (numbers from 0 to 9)
Possibilities for second space : 10 (since they can repeat)
Possibilities for third place : 10
Possibilities for fourth place : 10
10 × 10 × 10 × 10 = 10,000
If repetition of digits is allowed, there are 10,000 possible passcodes.