## Mental arithmetic

The boy in the front line is probably thinking: “As $10^2 + 11^2 + 12^2 = 365$ and $13^2 + 14^2 = 365$, therefore $\frac{10^2 + 11^2 + 12^2 + 13^2 + 14^2}{365} = \frac{2 \times 365}{365} = 2$”.

But why does the pupil behind, looks so scared while staring at him?

And what is he possibly trying to say to his teacher?