19 is only 1 away from 20, so you prefer to start by multiplying 20 times 5, which equals 100. Then we need to take away a squadron of 5, because there are actually only 19 squadrons, not 20. 100 take ...

There are 19 squadrons with 5 ships in each squadron. It looks like an attack force! Better call the space station and let them know. But how many ships are there ...