Question 30
Answer-format rule: round a non-integer answer to the nearest integer. If the calculated answer has more than five digits, give its last five digits.
Optional bonus question. Joe chooses a four-digit code using distinct digits from 0 to 9. Jane guesses; Joe gives the number of correct digits and the number in their correct positions. For example, for code 2561 and guess 2018, two digits are correct (2 and 1), and one is correctly placed (2). The five guesses and replies are in the table. The columns are guess number, guessed code, correct digits, correctly placed digits. Determine Joe’s code.
Optional bonus question. Joe chooses a four-digit code using distinct digits from 0 to 9. Jane guesses; Joe gives the number of correct digits and the number in their correct positions. For example, for code 2561 and guess 2018, two digits are correct (2 and 1), and one is correctly placed (2). The five guesses and replies are in the table. The columns are guess number, guessed code, correct digits, correctly placed digits. Determine Joe’s code.