#75 Seventh time lucky?
Septa wants to use a cash machine, but she has forgotten the PIN for her bank card. She has made six guesses so far, with no success:
5 7 2 6
7 3 5 8
1 1 9 1
7 6 2 8
4 8 8 2
9 3 0 7
Suddenly, she remembers that her PIN’s four digits are different. Her bank has a rule of “seven strikes and you’re out”, so she has just one more attempt before the machine swallows her card. As it happens, she had one correct digit in the right position in each of her guesses.…
