If you add the three numbers you get a perfect square:

\(\displaystyle 41 + 80 + 320 = 441 = 21^2\)

And... if you add any two of the numbers you also get perfect squares:

\(\displaystyle \begin{aligned}

41 + 80 &= 121 = 11^2 \\

80 + 320 &= 400 = 20^2 \\

41 + 320 &= 361 = 19^2

\end{aligned}\)

If it wasn't for Soroban's last post I wouldn't have thought of this. (Bow)