https://file.aiquickdraw.com/mathbot/file/1726603225026wh1gz3of.jpg

Let's estimate each calculation to identify the wrong answers:

**A) \( 31.45 \times 48.2 = 1515.89 \)**  
We can round the numbers for a rough estimate:  
\( 31.45 \approx 30 \) and \( 48.2 \approx 50 \).  
\( 30 \times 50 = 1500 \), which is quite close to \( 1515.89 \).  
So, **A** seems reasonable.

**B) \( (32.36 \times 5.9) + 25.1 = 2160.24 \)**  
Estimate:  
\( 32.36 \approx 30 \) and \( 5.9 \approx 6 \).  
\( 30 \times 6 = 180 \), and adding \( 25.1 \), we get approximately \( 205 \), which is much smaller than \( 2160.24 \).  
So, **B** seems wrong.

**C) \( 204.7 \times 0.813 = 16.641 \)**  
Estimate:  
\( 204.7 \approx 200 \) and \( 0.813 \approx 0.8 \).  
\( 200 \times 0.8 = 160 \), but the given result is \( 16.641 \), which is far too small.  
So, **C** is wrong.

**D) \( (298 + 97) \times 7.4 = 2923 \)**  
Estimate:  
\( 298 + 97 = 395 \).  
\( 395 \times 7.4 \approx 400 \times 7 = 2800 \), which is close to \( 2923 \).  
So, **D** seems reasonable.

### Conclusion:
The two incorrect answers are **B** and **C**.

Would you like more details or have any further questions? Here are some related questions for deeper understanding:

1. What are the benefits of using estimation in math?
2. How can rounding help simplify multiplication?
3. How do you identify when an answer is far off without exact calculations?
4. Why does small rounding not significantly affect larger estimates?
5. How would using more precise rounding affect the results?

**Tip:** Estimation is useful for quickly verifying results without the need for detailed calculation.

By estimating the answer to each calculation, work out which two of his answers are obviously wrong.

Learn how to estimate and identify incorrect answers in basic multiplication and addition problems. This task involves rounding, estimation, and mental math strategies. Suitable for students in Grades 5-7.

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