Explain why it is important to line up decimal numbers by their place value when you add or subtract them.

It is important because you could get a answer bigger or smaller than the actual answer. It could also make it easier and without having mistakes

You'll probably get the wrong answer unless you line up the decimals.

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It is important to line up decimal numbers by their place value when adding or subtracting them because it allows us to accurately perform the mathematical operation and maintain the correct value of each digit.

To understand why, let's consider an example where we have two decimal numbers: 2.35 and 1.47, and we want to subtract the second number from the first.

Step 1: Align the decimal points
We start by aligning the decimal points of both numbers. In this case, we have:

2.35
- 1.47

Step 2: Line up the place values
Next, we line up the digits according to their place values. The digit in the ones place is aligned with the other digit in the ones place, the digit in the tenths place is aligned with the other digit in the tenths place, and so on.

2 . 3 5
- 1 . 4 7

By lining up the decimals and the place values in this way, we ensure that each digit is being compared or combined with the corresponding digit from the other number. It prevents any misalignment or confusion.

Step 3: Subtract starting from the rightmost place value
Now, we can subtract starting from the rightmost place value (the hundredths place in this case) and work our way to the left. Subtracting the digits in the hundredths place gives us 5 - 7, which is -2. Since we can't have a negative digit in this case, we borrow 1 from the tenths place, making it 1.35.

2 . 3 5
- 1 . 4 7
____________
1 . 3 5

Step 4: Continue subtracting from left to right
Continuing to the next place value, we subtract the digits in the tenths place: 4 - 3. This gives us 1. We then subtract the digits in the ones place: 1 - 2. We need to borrow again from the tens place, making it 0. We are left with -1.

2 . 3 5
- 1 . 4 7
____________
0 . 8 8

Step 5: Simplify the result
The final result is 0.88. By correctly lining up the decimal numbers and their place values, we can accurately subtract them and obtain the correct result.

In general, lining up decimal numbers by their place value ensures that we are performing calculations accurately and maintaining the appropriate value for each digit. By doing this, we avoid errors and can confidently rely on the final result.