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 ...
THIS AIN'T YOUR FATHER'S MATH: Here's a bit of low-tech edtech that might just relieve some of the anxiety around multiplying double and triple digit numbers. The Magical Maths blog reports that the ...