Answer: 1120
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Step-by-step explanation:
Ignoring the slashes, there are 8 digits here. If we could tell those '1's and '2's apart, then we'd have 8! = 40,320 different codes. The exclamation mark indicates a factorial.
However, the '1's and '2's are indistinguishable. We have to divide by a!*b! = 3!*3! = 6*6 = 36 to account for this.
The a! = 3! = 6 is from the fact we have 3 copies of '1'.
The b! = 3! = 6 is from the fact we have 3 copies of '2'
Dividing by 36 gets us (40,320)/36 = 1120