Subtracting
Presentation
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Mathematics
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2nd Grade
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Practice Problem
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Easy
+1
Standards-aligned
brooke chapman
Used 33+ times
FREE Resource
9 Slides • 6 Questions
1
Subtracting using the counting back strategy on an open number line
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Place Value
We're going to review place value before we use an open number line to subtract large numbers. Let's get started!
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Multiple Choice
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Multiple Select
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Multiple Choice
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Multiple Select
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800 - 300 =
When we are finding the difference between two numbers we can use the count back strategy on an open number line. when we make an open number line, we starting by drawing a straight line with arrows on each end. When we subtract, we place the larger number at the far right of the line with a tick, and green dot to show where we are starting. In our equation, 800 is the larger number.
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800 - 300 =
We want to subtract 300, which is 3 hundreds. This is 3 hops of 100, counting back from 800. We know that when we subtract by hundreds, only the number in the hundreds place changes, and it decreases. We hop back 3 and count. We say 700, 600, 500. We land on 500, and that is where we stop. We mark our landing place with a red dot.We solved the equation by using an open number line, and we found that 800 – 300 = 500.
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Multiple Choice
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900 - 300 = 600
When using the counting back strategy where should you start on the number line, with 900 or 600?
How many jumps did you take to get from 900 to 600?
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860 - 210 =
Let's start by putting the larger number, 860, on the far right of the number line. We will use a green dot to show where we are starting.
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860 - 210 =
We are subtracting 210 from 860, so we can break apart 210 into 200 and 10, which is 2 hundreds and 1 ten.
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860 - 210 =
On our open number line, we will count back 2 hops of 100, or 200. We count back and say 760, 660. So, 860 – 200 = 660.
Now, we need to count back 1 ten. Count and hop back to 650. We landed on 650, so we draw a red dot to show where we landed. We have solved to find that 860 – 210 = 650.
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Multiple Choice
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530 - 220 = 310
When you break apart 220 into hundreds, tens and ones, how many of each group will you end up with?
How many jumps did you take to get from 530 to 220?
Subtracting using the counting back strategy on an open number line
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