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 ...

The process of multiplying three numbers together is similar to the process of multiplying two numbers, but it has one extra step. First, you multiply two of the numbers, then you multiply the third ...