Video Transcript
Subtracting 10s
In this video, we will learn how to
subtract a multiple of 10 from a multiple of 10 and model this with place-value
equipment.
A multiple of 10 is a number which
can be divided by 10 without a remainder. 10 is a multiple of 10. 20 is a multiple of 10, so are the
numbers 30, 40, 50, 60, 70, 80, 90, and 100. We can model multiples of 10 using
place-value equipment such as 10s blocks. This model shows the number 50
using five 10s, and it has no ones. Five 10s are 50. Let’s take away 10. If we take away one 10, instead of
having five 10s, we have four 10s. Four 10s are 40. Five 10s take away one 10 equals
four 10s. 50 take away 10 equals 40.
We subtracted a multiple of 10, 10,
from 50, which is also a multiple of 10. And we used place-value equipment
to help. Let’s try some questions to help us
practice subtracting a multiple of 10 from a multiple of 10. And we’ll use place-value equipment
to help.
Matthew is subtracting 10s. Eight 10s take away three 10s. Find the missing numbers. Eight 10s take away three 10s is
what 10s. 80 subtract 30 equals what.
In this question, we’re subtracting
a multiple of 10 from a multiple of 10. We know that Matthew has eight 10s,
and he subtracts three 10s. How many 10s does he have left? One, two, three, four, five. Eight 10s take away three 10s is
five 10s. What are five 10s worth? If our number has five 10s and no
ones, the number is 50. Let’s count in 10s to check. 10, 20, 30, 40, 50. 80 subtract 30 equals 50. Eight 10s take away three 10s
equals five 10s. 80 take away 30 equals 50.
Subtract to find the
difference. Hint: think about 10s and ones. Use base 10 blocks to help you. Six subtract four equals what. 60 subtract 40 equals what.
In this question, we’re told to
think about 10s and ones and use base 10 blocks to help us subtract four from six
and 40 from 60. If we have six base 10 blocks and
then we subtract four 10s, how many 10s do we have left? There are two. We know that six subtract four is
two. Six 10s subtract four 10s equals
two 10s. 60 subtract 40 equals 20. Six 10s are 60. If we subtract four 10s or 40, we
have two 10s left. And two 10s are 20.
Complete the following. 70 subtract 50 equals what.
We can model the number 70 using
10s blocks. How many 10s do we need to make the
number 70? There are seven 10s and no
ones. 10, 20, 30, 40, 50, 60, 70. We have to subtract 50. If we subtract 10, we’re left with
60. We subtracted two 10s, which is
20. Now, we’ve subtracted 30, 40,
50. We had seven 10s. We subtracted five 10s. And we’re left with two 10s. Two 10s are 20. So, 70 subtract 50 equals 20.
Complete the following: 60 subtract
what equals 10.
In this question, we have to find
the missing number. In other words, what do we need to
subtract from 60 to leave us with 10? We can use six 10s to model the
number 60. 10, 20, 30, 40, 50, 60. Let’s take away 10s until we’re
left with 10. We have 60. If we take away one 10, we’re left
with 50. If we take away two 10s, we have 40
left. If we take away three 10s, we’re
left with 30. If we take away four 10s, we have
20 left. And if we take away five 10s, we
have 10 left.
How much did we take away
altogether? Five 10s are 10, 20, 30, 40,
50. If we have six 10s or 60 and we
take away 50, we’re left with 10. The missing number is 50.
What have we learned in this
video? We’ve learned how to use
place-value equipment to subtract a multiple of 10 from a multiple of 10.
