Question 2
John cuts a 3 × 3 block from the May 1918 calendar, with each of its nine cells containing a date from 1 to 31. The three dates on the main diagonal are all prime. What is the date in the middle cell?
Editorial note: Use the usual Monday-first calendar convention. The source also prints an unrelated triangular-grid figure; it is retained separately for source fidelity and is not needed for this calendar problem.
Editorial note: Use the usual Monday-first calendar convention. The source also prints an unrelated triangular-grid figure; it is retained separately for source fidelity and is not needed for this calendar problem.