Make a number line to subtract
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Basics on the topic Make a number line to subtract
Mr Squeaks and Imani are having a snowball fight! Mr Squeaks notices that Imani’s pile of snowballs is a lot smaller than his and wants to work out the difference between them. To help Mr Squeaks we can show him how to subtract on a number line.
Subtraction using a number line
Mr Squeaks has noticed that he has thirty three snowballs whereas Imani only has seventeen! Mr Squeaks would like to know how many more snowballs he needs to throw to catch up with Imani. To do this he needs to work out the difference between their amounts. We can use number line subtraction to find the answer.
How to subtract on a number line
First of all Mr Squeaks can put thirty three on the right side of the number line as this is the number we are starting with. We can then split seventeen into ten and seven to make it easier to subtract. * Starting at thirty three we will subtract ten to get to twenty three. * We will then count back in ones until we have subtracted seven more. * We will land on sixteen. Therefore, Mr Squeaks needs to throw sixteen more snowballs, I wonder if he’ll be able to catch up!
Subtraction on a number line
For more on subtraction with a number line and a further number line subtraction activity, have a look at our number line subtraction worksheets.
Transcript Make a number line to subtract
Mr Squeaks and Imani are having a snowball fight! The first one to throw all of their snowballs will win! Mr Squeaks thinks that he can be the winner if he stays focused! "This is harder than I thought!" Imani has already thrown quite a lot of snowballs and Mr Squeaks has realised that she only has SEVENTEEN in her pile now! Mr Squeaks still has thirty-three! Hmm, I wonder what the difference is between their piles? Let's find out by : "Making a Number Line to Subtract" Mr. Squeaks wants to know the difference of the piles to find out how many more snowballs he needs to throw. His pile has thirty-three, while Imani's has seventeen, so we can find thirty-three minus seventeen. One way he can do this is by making a number line to subtract. When subtracting using a number line, always start by putting the larger number on the RIGHT side. We're subtracting seventeen from thirty-three, so we will put thirty-three on the right side. The next step is to count backwards by the second number. Our next number is seventeen, which we can break apart into one TEN and seven ONES. Once we count back ten, we can count back seven ones. Finally, circle the number we landed on. This is our answer. We landed on sixteen, so, Mr. Squeaks needs to throw a lot more snowballs to win! "Ahh that's much better!" Mr Squeaks thinks that his new machine will help him to catch up with Imani! "Oh! She's STILL winning?" While Mr. Squeaks was creating a machine, snowballs were added to his pile and now he needs to subtract again so he can catch up. If Mr. Squeaks has forty-four snowballs, and Imani has twenty-three, how many does he need to throw? Remember, when using a number line to subtract ALWAYS start by putting the larger number on the RIGHT. Then count backwards by small amounts of the next number. Our next number is twenty-three, which we can break into twenty and three. We can count backwards by ten TWICE to make twenty. Then we can count back by three ones to find the answer. We landed on twenty-one. Mr. Squeaks needs to throw twenty-one snowballs! "Aww! There goes my machine. I'll need to fix that!" While Mr. Squeaks is fixing his machine, he notices the piles have changed again. Mr. Squeaks now has fifty-eight snowballs while Imani has thirty-four. How many does Mr. Squeaks need to throw this time? In order to find out we need to subtract thirty-four from fifty-eight. Remember to start by putting the larger number on the RIGHT. The larger number is fifty-eight, so this goes on the right. Our next number is thirty-four, which we can break into small amounts to help us count. There are a few different ways to do this. Let’s have a look at one way. Here we counted backwards three tens and four ones. You can count backwards in different ways, but should always end on the same number. Which number did we end on here? Twenty-four! So, Mr. Squeaks needs to throw twenty-four snowballs. "That's better, now I can throw more snowballs with my machine again!" While he was fixing his machine, Imani threw a lot of her snowballs and Mr. Squeaks threw none! But, before we see who won the snowball throwing competition, let's review. When subtracting using a number line, start by putting the larger number on the RIGHT side. Next, count backwards by the second number. Remember, you can break apart the second number into smaller amounts like tens and ones. Finally, circle the number we landed on last. This is our answer. Now, let's see who is throwing more snowballs! "I'm on a roll, look at me go!" "Wait a second, where did Imani go?" "Imani, are you under my snowballs?"
Make a number line to subtract exercise
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What are the steps to subtract on a number line?
HintsThis shows the first step that was taken when solving this subtraction.
Look at this image showing all 4 steps when solving a subtraction problem on a number line to help remember the order.
SolutionThe steps are:
- Start by putting the number you are subtracting from on the right side of the number line.
- Partition the number you are subtracting into tens and ones, ready to count back.
- Count back in tens and then ones along the number line.
- Finally, see what number you landed on.
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How many snowballs?
HintsWhat is the first step? Use a number line and put the number you are subtracting from on the right.
What is the second step? Partition the number you are subtracting. What can 22 be partitioned into?
Count back the tens then the ones.
SolutionThe steps to solve the problem are:
- Put the number you are subtracting from, 37, on the right hand side of the number line.
- Partition the number you are subtracting, 22, into 20 and 2.
- Count back along the number line, first the tens, then the ones.
- Finally, you should land on 15. This is the answer.
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Melting snowballs.
HintsCreate a number line and put the number you are subtracting from on the right.
Remember that when counting back, to count back in tens first then ones.
Read the word problem carefully to see which number is to be subtracted and should be partitioned.
Solution- The steps to solve 89 - 23 are as follows:
- Put 89 on the right side of the number line.
- Partition 23 into 20 and 3.
- Count back in the tens first, to 79 then 69.
- Count back in the ones next, to 68 then 67 then 66.
- As 66 is the final number you land on, this is the answer.
- 89 - 23 = 66
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How many more snowballs does Mr. Squeaks have?
HintsTo find the difference, subtract the smaller number from the larger number.
Use the steps of drawing a number line, putting the larger number on the right and then partitioning the smaller number.
Remember to jump back in steps of tens and then ones.
Solution- 53 - 32 = 21 is shown in the image.
- After putting 53 on the right side of the number line, we can partition 32 into 30 and 2. First count back three tens starting at 53: 43, 33, 23; then count back two ones starting from 23: 22, 21. So the answer is 21.
- 85 - 55 = 30
- After putting 85 on the right side of the number line, we can partition 55 into 50 and 5. First count back five tens starting at 85: 75, 65, 55, 45. 35; then count back five ones starting from 35: 34, 33, 32, 31, 30. So the answer is 30.
- 58 - 36 = 22
- After putting 58 on the right side of the number line, we can partition 36 into 30 and 6. First count back three tens starting at 58: 48, 38, 28; then count back six ones starting from 28: 27, 26, 25, 24, 23, 22. So the answer is 22.
- 77 - 51 = 26
- After putting 77 on the right side of the number line, we can partition 51 into 50 and 1. First count back five tens starting at 77: 67, 57, 47, 37. 27; then count back one starting from 27: 26. So the answer is 26.
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How many snowballs does Imani have left?
HintsThe tens have already been counted back. What needs to be counted back next?
What is the final number that you land on? This is the answer.
Solution- First, the number you are subtracting from has been written on the right.
- 23 has been partitioned into 20 and 3.
- The tens have already been counted back, to 34 then 24.
- The missing gaps were then to count back in ones to reach, 23, 22, 21.
- As 21 was the last number landed on, this is the answer.
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Solve the subtractions.
HintsCreate a number line and put the number you are subtracting from on the right. Then partition the smaller number and count back in tens then ones.
Solution- 54 - 23 = 31 ✅
- 62 - 41 = 28 ❌ 62 - 41 = 21 ✅
- 86 - 37 = 51 ❌ 86 - 37 = 49 ✅
- 63 - 35 = 28 ✅
- 164 - 23 = 141 ✅
