Question 27
Is it possible to fill an $n\times n$ table with numbers $1$ and $2$ such that the sum of the numbers in each column is a multiple of $5$ and the sum of the numbers in each row is a multiple of $7$? Solve this:
- **(a)** for $n=9$.
- **(b)** for $n=12$.
(Tomáš Bárta)
- **(a)** for $n=9$.
- **(b)** for $n=12$.
(Tomáš Bárta)