Question 7
Let $A$ be a $3\times3$ array of one to nine, each once. Form $B$ by $b_{ij}=|r_i-c_j|$, where $r_i$ is the sum of row $i$ of $A$, and $c_j$ the sum of column $j$. Can $B$ also contain one to nine each once?
xIMC · IMC 2007 — Keystage 3 (IWYMIC) — team