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(Replacing items)
What if after picking an item, you put it back? You can pick the same item again.
Example: Lock with 3 digits, each digit 0-9. How many combinations? Each position has 10 choices, and choices repeat.
Total: 10 × 10 × 10 = 10³ = 1000.
This is different from standard permutations. Repetition changes the count.
