I accept DarnItJimImAnEngineer's assertion that N = 10, but I haven't attempted to prove it. The question asked for the unit digit of N, which is 0 if N = 10.

I accept DarnItJimImAnEngineer's assertion that N = 10, but I haven't attempted to prove it. The question asked for the unit digit of N, which is 0 if N = 10.