Video Transcript
Dividing by 10
In this video, we will learn how to
use various strategies to divide by 10 including using models and the times table
facts. This picture shows 60 bowling
pins. And they’ve been grouped by 10. When we share an amount of objects
into equal groups, we are dividing. The number we’re dividing is
60. This is the total number of bowling
pins. In maths, this number or this
amount is called the dividend. The number we’re dividing by is
called the divisor.
In this question, we’ve divided our
skittles or bowling pins into equal groups of 10. So in this question, the divisor is
10. We’ve divided our 60 bowling pins
into groups of 10. How many groups of 10 did we
make? One, two, three, four, five,
six. 60 divided by 10 equals six. We have 60 skittles. We divided them into equal groups
of 10. And there are six groups. We call this number in the division
sentence the quotient. This is the number we get if we
divide 60 by 10.
To help us calculate 60 divided by
10, we’ve used a picture. This picture helps us to visualize
the division problem. We can also use models or maths
equipment to help us when we’re dividing by 10. We could use a tens block to
represent each group of 10 skittles. Can you remember how many skittles
there were? 60. So here is 10, 20, 30, 40, 50,
60. We know that six 10s make 60. Six times 10 is 60. How could we write this as a
division fact? We have 60 orange blocks. We’ve divided them into equal
groups of 10. And there are six groups or six
tens blocks.
When we’re dividing by 10, we could
draw a picture, make a model, and use our knowledge of the 10 times table. We can also use a number line to
help us divide by 10. To divide 60 by 10 using a number
line, we could start at 60 and then count back in tens until we reach zero. So we’re starting at 60, 50, 40,
30, 20, 10, zero. How many times did we count back 10
or take away 10? One, two, three, four, five,
six. There are six 10s in 60. So 60 divided by 10 equals six. We could also use the number line
to count forward in tens. One times 10 is 10, two times 10 is
20, three times 10 is 30, four times 10 is 40, five times 10 is 50, six times 10 is
60.
Again, we’ve found that there are
six 10s in 60. So we can say that 60 divided by 10
equals six. We’ve learned lots of ways to
divide by 10. We can use pictures to help. We can use models such as tens
blocks. We can use our knowledge of the 10
times table. And we can count back in tens or
forward in tens on a number line. Let’s practice what we’ve learned
about dividing by 10 with some questions.
A teacher wants to equally
distribute 80 notebooks among 10 students. Complete the equation to find the
number of notebooks each student received. What divided by what equals
what. Is the equation 80 divided by 10
equals 90, 10 divided by 80 equals eight, 80 divided by 10 equals 70, or 80 divided
by 10 equals eight?
Let’s read the question again more
carefully. We know that the teacher has 80
notebooks. And she wants to distribute them
equally. This is another way of saying share
or divide. We already know this is a division
problem because we can see the division symbol. So the teacher wants to share her
80 notebooks between her 10 students. And we have to complete the missing
numbers in the equation. In other words, we have to complete
the division sentence. We know that the teacher has 80
notebooks, so let’s model the number 80. 10, 20, 30, 40, 50, 60, 70, 80. We’ve used 80 counters to model the
80 notebooks. We can cross out this division
equation. We know the number of notebooks is
80, not 10. 10 is the number of students.
We’re dividing by 10 because the
teacher wants to share her 80 notebooks equally between 10 students. We’ve divided our 80 counters into
groups of 10. All of these equations say 80
divided by 10. Is 80 divided by 10 90, 70, or
eight? How many groups of 10 were we able
to make using our 80 counters? Let’s count them. One, two, three, four, five, six,
seven, eight. 80 divided by 10 equals eight. And we took 80 counters and divided
them into groups of 10. There were eight groups. So the correct equation is 80
divided by 10 equals eight. We used our model to help us
complete the division sentence. 80 divided by 10 equals eight.
Use the number line to calculate 30
divided by 10.
In this question, we have to
calculate 30 divided by 10. And we’re going to use the number
line to help. We can see from the number line
that we’re starting at number 30 and counting back in tens. Counting backwards by 10 is the
same as subtracting 10. 30 take away 10 equals 20. 20 take away 10 equals 10. And 10 take away 10 equals
zero. How many times did we count
backward by 10? Three times. 30 divided by 10 equals three. We counted back in tens three
times. There are three 10s in 30.
Here are two number sentences that
have a missing number. What times 10 equals 20. 20 divided by 10 equals what. What is the missing number that
completes both of the number sentences? Is it 30, three, 10, or two?
We’re being asked to find these two
missing numbers. And we’re told that the missing
numbers are the same number. So which number would fit in both
of these number sentences? In this sentence, we have to find
the number that we multiply by 10 to give us a product of 20. What times 10 is 20? We know that one lot of 10 is 10
and two lots of 10 makes 20. One times 10 is 10; two times 10 is
20. We found our first missing
number. We modeled the number 20 using
blocks of 10. And we used our knowledge of the 10
times table to say that two times 10 equals 20. If two times 10 is 20, then 20
divided by 10 equals two. This is the missing number that
completes both number sentences. Two times 10 equals 20. 20 divided by 10 equals two.
What have we learned in this
video? We’ve learned how to use different
strategies to divide by 10. We used pictures to help us
visualize problems, models using maths equipment like counters and tens blocks. We used number lines to help us
count in tens and count backward by 10. We also learned how to use our
knowledge of the 10 times table to help us divide by 10. We’ve learned lots of different
strategies to divide by 10.
