Make a number line to subtract

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Make a number line to subtract
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Contents

What do you learn about making a number line to subtract?

There are many different strategies and tools to subtract, one of those is making a number line to subtract. When subtracting using a number line...

  • First, put the larger number on the right side of the number line.

  • Next, skip count back the amount of the second number. Remember, you can break apart the second number into smaller amounts like tens and ones to help skip count.

  • Finally circle the number that you land on, this is the answer!

Transcript Make a number line to subtract

: "Alright, first one to throw all of their snowballs wins!" : "I know I can do it, I just have to stay focused!" : "This is harder than I thought!" : "Hmm, Imani has already thrown a lot, she has seventeen in her pile right now." : "I have thirty-three, I wonder what the DIFFERENCE is between our piles." : "Make 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 skip count backward 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 ended on last (...) 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!" : "Now I can 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 skip count backward small amounts of the next number. Our next number is twenty-three, which we can break into twenty and three to skip count. We can skip count backward by ten TWICE (...) to get twenty. Then we can count backward 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 fifty-eight minus thirty-four. Remember to start by putting the larger number on the RIGHT. Our next number is thirty-four, which we can break into small amounts to help us skip count. There are a few different ways, let’s see one way. Here we skip-counted backward three tens and four ones. You can skip count backward different ways, but should always have the same ending number. What 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 contest, let's review. When subtracting using a number line... Start by putting the larger number on the RIGHT side. Next, skip count backward the second number. Remember, you can break apart the second number into smaller amounts like tens and ones. Finally, circle the number we ended 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

Would you like to practice what you’ve just learned? Practice problems for this video Make a number line to subtract help you practice and recap your knowledge.
  • What are the steps to subtract on a number line?

    Hints

    This shows the first step that was taken when solving this subtraction problem.

    Look at this image showing all 4 steps when solving a subtraction problem on a number line to help remember the order.

    Solution

    The steps are:

    1. Start by putting the number you are subtracting from on the right side of the number line.
    2. Partition the number you are subtracting into tens and ones, ready to count back.
    3. Count backward by tens and then ones along the number line.
    4. Finally, see what number you land on.
  • How many snowballs?

    Hints

    What 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 in to?

    Count back the tens then the ones.

    Solution

    The steps to solve the problem are:

    1. Put the number you are subtracting from, 37, on the right hand side of the number line.
    2. Partition the number you are subtracting, 22, into 20 and 2.
    3. Count backward along the number line, first the tens, then the ones.
    4. Finally, you should land on 15. This is the answer.
  • Melting snowballs.

    Hints

    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 being 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 in to 20 and 3.
    • Count back by tens first, to 79 then 69.
    • Count back by ones next, to 68 then 67 then 66.
    • As 66 is the final number you land on, this is the answer.
    • 89 - 23 = 66
  • How many more snowballs does Mr. Squeaks have?

    Hints

    To 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 by 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.
    -------------------------------- For the other questions:
    • 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.
  • How many snowballs does Imani have left?

    Hints

    The 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 in to 20 and 3.
    • The tens have already been counted back, to 34 then 24.
    • The missing gaps were then to count back by ones to reach, 23, 22, 21.
    • As 21 was the last number landed on, this is the answer.
  • Solve the subtraction equations.

    Hints

    Create a number line and put the number you are subtracting from on the right. Then partition the smaller number and count backward by 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 ✅