20 pigeons sat on the branches of a tree. A man hit 1 pigeon with a cannon. How many were left on the tree?

I would say none. The other 19 flew away.

To find out how many pigeons are left on the tree after one is hit with a cannon, you need to subtract the number of pigeons that left the tree due to being hit.

Given that initially, there were 20 pigeons, and one pigeon was hit, we need to subtract one from the initial count.

So, 20 - 1 = 19 pigeons would be left on the tree after one is hit with a cannon.