An animated guide in which fractions multiply to make baby fractions and a rather violent fraction divides numbers with a chainsaw. Use to illustrate the processes of multiplying fractions, and ...

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 ...