Video Transcript
If you know that two times 10
equals 20, find four times 10.
In this question, we’re told to
use one fact to help us find another. The fact we’re given is two
times 10 equals 20. And we have to find four times
10. We’re multiplying both numbers
two and four by 10. How can we use two times 10 to
help us find four times 10? Four is double two. To get from two to four, we
need to multiply two by two. Doubling is the same as
multiplying by two. So to find the answer to four
times 10, we need to double 20. Double 20 is 40. Two 10s are 20. Four 10s are 40.
We used the fact that two times
10 is 20 to help us find four times 10. We used our knowledge of
doubling to help. Four times 10 is 40.
