Maysa made a mistake when she calculated \(3.5 - 2.46\). She wrote the answer as \(1.16\), but that's not correct. Let's figure out what she did wrong and how we can help her understand.
First, let's stack the numbers to see the subtraction step by step:
3.50 (which is the same as 3.5)
- 2.46
Now we start subtracting from the rightmost side. We need to make sure we line up the decimal points and subtract each column carefully.
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Subtract the hundredths column: 0 - 6. Since you can't subtract 6 from 0, we need to borrow. We borrow 1 from the tenths column (which is 5, making it 4) and add 10 to the hundredths, turning it into 10. So now we have:
- 10 - 6 = 4
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Subtract the tenths column: Now we have 4 (after borrowing) - 4 = 0.
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Subtract the ones column: 3 - 2 = 1.
Putting it all together, we get:
3.50
- 2.46
-------
1.04
So the correct answer to \(3.5 - 2.46\) is \(1.04\).
How to Help Maysa
To help Maysa understand where she went wrong, we can use a number line or place-value blocks.
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Number line: We can draw a number line starting at 0 up to 4. Show her where \(3.5\) is and then count backwards \(2.46\) steps. This visual representation helps her see how far she needs to go back.
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Place-value blocks: We can use blocks to represent the numbers. Show her 3 whole blocks and 5 tenth blocks. Then, have her take away 2 whole blocks and 4 tenths, which will visually show her how many blocks are left, helping her see that the answer is actually 1 whole and 4 tenths (or \(1.04\)).
By using these models, she can grasp the concept of borrowing and how to line up the numbers correctly in subtraction. Maysa will learn that careful organization with decimal points is very important in getting the right answer!
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