Part A
Use mental math to solve the problem 8.02−5.98
.
Question 2
Part B
Explain the method of mental math that you used to find the answer. Be specific with each step you took.
(4 points)
Part A: Using mental math to solve 8.02 - 5.98.
To solve this problem using mental math, we can start by subtracting the whole numbers:
8 - 5 = 3
Then, we can subtract the decimal parts:
0.02 - 0.98 = -0.96
So the final answer is 3 - 0.96 = 2.04.
Part A:
To solve the problem using mental math, I subtracted 5.98 from 8.02 as follows:
8.02 - 5.98 = 2.04
Part B:
To perform the mental math calculation, I used the vertical subtraction method. Here are the specific steps I took:
1. Begin by aligning the decimal points of the numbers: 8.02 and 5.98.
8.02
- 5.98
2. Starting from the rightmost digit, subtract 8 from 2. Since 8 is larger than 2, we regroup.
- Subtract 8 from 12 (12 is obtained by borrowing one from the 0 in the tens place, making it 10).
8.02
- 5.98
2
3. Now, move on to the next column and subtract 9 from 0. Since 0 is smaller than 9, we regroup again.
- Subtract 9 from 10 (10 is obtained by borrowing one from the 0 in the hundreds place, making it 9).
8.02
- 5.98
2
10
4. Finally, subtract 5 from 8, which gives us 3.
8.02
- 5.98
2
10
3
5. Therefore, the final answer is 2.04.
Part A: To solve the problem 8.02 - 5.98 using mental math, you can follow these steps:
1. Start by subtracting the whole numbers: 8 - 5 = 3.
2. Next, subtract the decimal parts: 0.02 - 0.98 = -0.96.
3. Finally, add the results from step 1 and step 2: 3 + (-0.96) = 2.04.
Therefore, the solution to 8.02 - 5.98 using mental math is 2.04.
Part B: The method I used for mental math to find the answer step by step is as follows:
1. I recognized that 8 - 5 is equal to 3. Since the whole numbers are smaller, I decided to start by subtracting the whole numbers.
2. Next, I visualized the decimal parts 0.02 and 0.98 and realized that 0.02 is very close to 0. I approximated it to 0 for easier mental calculation. Then, I subtracted 0 from 0.98, which gave me 0.98.
3. Finally, I added the result from step 1 (3) with the result from step 2 (0.98). The addition gave me a final result of 2.98.
However, since I approximated 0.02 to 0, there is still a small difference left. The actual difference between 0.02 and 0 is 0.02. By recognizing this, I adjusted my previous result of 2.98 by subtracting 0.02 to get the correct answer of 2.04.
Using this mental math method, I was able to solve the subtraction problem 8.02 - 5.98 accurately and efficiently.