Below are given 4 digit passwords using symbols $M,N,1,0,8,9$
$$\boxed{N}\boxed{N}\boxed{1}\boxed{1} \cdot \boxed{0}\boxed{9}\boxed{N}\boxed{M}\cdot \boxed{N}\boxed{N}\boxed{N}\boxed{N}$$
How many ways can you choose an ordered 4−tuple of these characters given that repetitions are allowed and given that at least one of M,N must be used?
I've no idea concerning what this question actually means. Could you assist me?
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