Video Transcript
Multiplying by Three
In this video, we’re going to learn
how to model multiplication by three and recite the three times table up to 10 times
three.
Let’s start by modeling the three
times table. This model shows one times
three. One times three is the same as
saying one group of three. When we say the three times table,
we’re counting in groups of three. Two times three is six. Three groups of three or three
times three is nine. Four times three or four groups of
three is 12. Five threes or five times three is
15. Six groups of three or six times
three is 18. Seven times three is 21. Eight groups of three or eight
times three is 24. Nine threes are 27. And 10 groups of three or 10 times
three equals 30.
When we’re multiplying by three, a
really useful skill to have is to be able to count in threes. Let’s practice counting in threes
using a number line. Three, six, nine, 12, 15, 18, 21,
24, 27, 30.
Another way to learn the three
times table is to practice reciting it. One times three is three, two times
three is six, three times three is nine, four times three is 12, five threes are 15,
six threes are 18, seven threes are 21, eight threes are 24, nine threes are 27, and
10 times three is 30.
Now that we’ve learned how to model
the three times table using groups of three, learned how to count in threes on a
number line, and practiced reciting the three times table, let’s try some
questions.
What are the three missing numbers
in this table?
We’re shown a multiplication
table. And we’re multiplying by three. We have to multiply the numbers in
the top row by three. One times three is three. Two times three is six. Now, we’ve reached a missing
number. What is three times three? Here are three groups of three. One three is three, two threes are
six, three threes are nine. So, we know the first missing
number is nine.
Three, six, nine, 12, 15, 18. To find this missing number, we
have to multiply seven lots of three. What is seven times three? We know that six threes are 18. This is the last number in our
table before the missing number. We know that seven threes are three
more than 18. Seven times three is 21. Three more than 18 is 21. We found our second missing
number.
Three, six, nine, 12, 15, 18, 21,
24, 27. What’s our last missing number? What is 10 times three? 10 times three is one of the
multiplication facts in the three times table that’s quite easy to remember. 10 times three is 30. We modeled groups of three to help
us multiply by three. Three, six, nine, 12, 15, 18, 21,
24, 27, 30. The missing numbers are nine, 21,
and 30.
Find the missing numbers. Two times three equals what. What times three equals 12. Six times three equals what.
In this question, we’re shown a
number line with blocks of bricks. The bricks are grouped in
threes. We need to use the number line to
help us find the missing numbers. Our first missing number is two
times three. Let’s use the number line to help
us find two times three. We can see that one times three is
three and two times three is six. So, the first missing number is
six. Two times three is six.
What did we multiply by three to
make 12? Let’s count in threes. Three, six, nine, 12. One group of three is three, two
groups of three is six, three groups of three is nine, and four groups of three is
12. Our second missing number is four
because four times three equals 12.
Now, our final missing number is
six times three. If four threes are 12, then five
threes are 15. Three more than 15 is 18. So, six threes are 18. Three, six, nine, 12, 15, 18. We use the number line and the
blocks to help us count in threes. The missing numbers are six, four,
and 18. Two times three is six, four times
three is 12, and six times three is 18.
In multiplying by three, each row
is three more than the previous one. One times three equals three, two
times three equals six, three times three equals nine. Complete the following: Four times
three equals what. Complete the following: Five times
three equals what.
This question is all about
multiplying by three. We’re shown some models and told
that each row is three more than the previous one. One times three is three, two times
three is six, and three times three is nine. We have to complete four times
three and five times three.
We already know that one times
three is three, two times three is six, and three times three is nine. So, four times three is three more
than nine. Four times three is 12. And we know that five times three
is three more than 12. Three more than 12 is 15. So, five multiplied by three equals
15. The missing numbers are 12 and
15. Four times three equals 12, and
five times three equals 15.
What is three times six?
In this question, we’re being asked
to multiply three times six. Maybe you know how to count in
sixes and your six times table. We’re learning how to multiply by
three. So, we could write the
multiplication expression as six times three.
To help us multiply these two
numbers, we could use our number line. To multiply six times three, we
could count in threes six times on our number line. We could skip count by three. We need to count forward in threes
six times. Three, six, nine, 12, 15, 18. One times three is three, two times
three is six, three times three is nine, four times three is 12, five times three is
15, six times three is 18. Three times six or six times three
is 18.
What have we learned in this
video? We’ve learned how to model
multiplication by three using arrays, counters or dots, and number lines. We’ve also learned how to recite
the three times table up to 10 times three.
