Find out what multiples are and how to sort multiples of 2 and 5. Doubling numbers Learn how to make doubles using ten frames, addition and multiplication. Counting in twos, threes, fives and tens ...
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 ...