Question 5
Start with a 3 × 3 grid filled with 1s. At each step, select a 2 × 2 region and add 1 to all four entries in it. Which of the following grids can result after several steps?
Source correction for this exercise: Replace the initial value 1 by 0 in every cell. As originally printed with 1, none of A–E is possible. Answer the corrected version; the original wording is retained above for provenance.
Source correction for this exercise: Replace the initial value 1 by 0 in every cell. As originally printed with 1, none of A–E is possible. Answer the corrected version; the original wording is retained above for provenance.
