Rule (column-wise): Each bottom entry equals the sum of the squares of the three numbers above it in that column.
\[
\begin{aligned}
\text{Col 1: } 7^2+5^2+3^2 &= 49+25+9 = 83 \quad \checkmark \\
\text{Col 2: } 6^2+4^2+2^2 &= 36+16+4 = 56 \quad \checkmark \\
\text{Col 3: } 8^2+9^2+1^2 &= 64+81+1 = 146
\end{aligned}
\]
\[\boxed{146}\]