instance, if you want to multiply 16 by 22, it is easy if you see 22 as 2 × 11. Then you multiply 16 by 2
to get 32, and use the shortcut to multiply 32 by 11.
Let’s try multiplying 7 by 33.
7 × 3 = 21
21 × 11 = 231 Answer
How about multiplying 14 by 33? Thirty-three is 3 times 11. How do you multiply 3 by 14? Fourteen
has factors of 2 and 7. To multiply 3 × 14 you can multiply 3 × 2 × 7.
3 × 2 = 6
6 × 7 = 42
42 × 11 = 462 Answer
You can think of the problem 14 × 33 as 7 × 2 × 3 × 11. Seven times 3 × 2 is the same as 7 × 6, which
is 42. You are then left with 42 × 11. Teaching yourself to look for factors can make life easier and can
turn you into a real mathematician.
One last question for this chapter: how would you multiply by 55? To multiply by 55 you could
multiply by 11 and 5 (5 × 11 = 55) or you could multiply by 11 and 10 and halve the answer. Always
remember to look for the method that is easiest for you.
After you have practised these strategies, you will begin to recognise the opportunities to use them
for yourself.