Video Transcript
Multiplying by Four
In this video, we will learn to
model multiplication by four and recite the four times table. I think our four-legged friend has
decided to keep his four legs on the ground. Lots of animals have four legs. Did you notice that the dogs paw
prints are in groups of four? We could use these paw prints to
help us practice counting in fours. We know one lot of four is
four. Two fours are eight. Three lots of four is 12. Four times four is 16. Five fours are 20. Six fours are 24. Seven fours are 28. Eight fours are 32. Nine fours are 36. And 10 fours are 40.
Let’s practice counting in fours
one more time. Four, eight, 12, 16, 20, 24, 28,
32, 36, 40. Being able to skip count in fours
helps us to learn our four times table. To help us learn the four times
table, we can use models, like these groups of four counters and number lines. We’re going to use this number line
to help us count in fours. One times four is four, two times
four is eight, three times four is 12, four times four is 16, five times four is 20,
six times four is 24, seven times four is 28, eight times four is 32, nine times
four is 36, and 10 times four is 40.
We can also use our knowledge of
the two times table and doubling to help us multiply by four. Double two is four. So to help us find six times four,
we could use our knowledge of the two times table. If we know that six times two is
12, we know that six times four is double this. And 12 plus 12 or double 12 is
24. So far, in this video, we’ve
learned how to skip count in fours using models and number lines to help. We’ve practiced reciting the four
times table. And we’ve learned how to use our
knowledge of the two times table and doubling to help us multiply by four. Let’s practice the strategies we’ve
learned for multiplying by four by answering some questions now.
We can skip count by fours using a
number chart to help us multiply by four. Use skip counting to find four
times two. Use skip counting to find four
times nine.
In this question, we’ve been given
a number chart to help us multiply by four. And we can see that some of the
numbers are orange. These are the numbers which we get
when we multiply by four. These are the multiples of
four. Four, eight, 12, 16, 20, 24, 28,
32, 36, 40. We’re told to use this chart to
help us find four times two. To find four times two, we need to
skip count by four two times. One, two, four, eight. Four times two is eight.
Now we need to skip count by four
nine times to find four times nine. We know that two fours are eight,
three fours are 12, four times four is 16, five times four, six times four, seven
times four, eight fours, nine fours. Four, eight, 12, 16, 20, 24, 28,
32, 36. Four times nine is 36. We skip counted by fours to help us
multiply by four. Four times two is eight and four
times nine is 36.
Use the number line to find the
product: Three times four equals what. Hint: How many jumps of four should
you make?
In this question, we have to find
the product of three times four. And we’re given a hint. How many jumps of four should we
make on the number line? One jump has been made already, and
we know that one times four is four. To find three times four, we need
to make three jumps of four. The first one has been done. One four is four, two fours are
eight, and three fours are 12. Four, eight, 12. We needed to skip count by fours to
find three times four. Three times four equals 12.
Find the missing numbers. Hint: Use the array to help
you. Five times four equals what. Six times four equals 20 plus
what. Six times four equals what.
We have to find the three missing
numbers. And we’re told to use the array to
help us. First, we need to find five times
four. One lot of four or one row of four
is four. Two fours are eight. Three fours are 12. Four fours are 16. Five lots of four are 20. If five times four or five lots of
four are 20, to find six lots of four, we just need to add another four to 20. Six times four is equal to 20 plus
four. 20 plus four is 24. So six times four is 24. We used the array to help us find
the missing numbers.
Use three times four equals 12 to
find six times four.
In this question, we have to find
the product of six and four. And we are told to use the fact
that three times four is 12 to help. We know that three times four is
12. So to find six lots of four, we
just need to double 12. Double 12 is 24. Two lots of 12 are 24. So we found six times four by
doubling three times four. Six times four is 24.
What is nine times four?
We could use our knowledge of the
four times table to help us answer this question. We know that 10 times four is
40. So to find nine times four, we just
need to subtract four from 40. Four less than 40 is 36. We use the fact that 10 times four
is 40 to help us find that nine times four is 36. The answer is 36.
What have we learned in this
video? We’ve learned how to use models to
help us multiply by four and how to recite the four times table.
