Estimate the result, and then multiply in writing.
[table]
| 40-2=80 | Estimation | Calculation |
|---|---|---|
| 43 * 2 | 26 * 3 | 74 * 6 | 87 * 4 |
| Estimation: 700 * 4 = | Estimation: | Estimation: | Estimation: |
| 742 * 4 | 1896 | 1937 | 4836 |
| . | | | |
[/table]
6)
Answer (2)
We estimated the multiplication problems by rounding each number to the nearest ten, then calculated the exact answers using written multiplication. The estimates were close but not always accurate. The exact results for the multiplications are 86, 78, 444, and 348 respectively.
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Estimate the results of the multiplication problems by rounding each number to the nearest ten.
Calculate the exact results of the multiplication problems using written multiplication.
Compare the estimated results with the exact results.
The exact results are: 43 × 2 = 86 , 26 × 3 = 78 , 74 × 6 = 444 , 87 × 4 = 348 .
Explanation
Understanding the Problem The problem asks us to estimate the results of multiplication problems and then perform the written multiplication to find the exact answers. We will then compare our estimations with the exact answers to see how close we were.
Estimating the Results First, let's estimate the results of the multiplication problems by rounding each number to the nearest ten.
Estimating 43 x 2 For 43 × 2 , we round 43 to 40. So the estimation is 40 × 2 = 80 .
Estimating 26 x 3 For 26 × 3 , we round 26 to 30. So the estimation is 30 × 3 = 90 .
Estimating 74 x 6 For 74 × 6 , we round 74 to 70. So the estimation is 70 × 6 = 420 .
Estimating 87 x 4 For 87 × 4 , we round 87 to 90. So the estimation is 90 × 4 = 360 .
Calculating Exact Results Now, let's perform the written multiplication for each problem to find the exact answers.
Calculating 43 x 2 43 × 2 = 86
Calculating 26 x 3 26 × 3 = 78
Calculating 74 x 6 74 × 6 = 444
Calculating 87 x 4 87 × 4 = 348
Comparing Estimations and Exact Results Comparing the estimations with the exact answers:
For 43 × 2 , the estimation was 80 and the exact answer is 86.
For 26 × 3 , the estimation was 90 and the exact answer is 78.
For 74 × 6 , the estimation was 420 and the exact answer is 444.
For 87 × 4 , the estimation was 360 and the exact answer is 348.
Final Answer The exact results of the multiplications are: 43 × 2 = 86 26 × 3 = 78 74 × 6 = 444 $87 \times 4 = 348
Examples
Estimating and multiplying are fundamental skills used daily. For example, when shopping, you might estimate the total cost of your items to ensure you don't exceed your budget. If you buy 3 items priced at $26 each, you can quickly estimate the cost as $30 \times 3 = $90. Then, you can calculate the exact cost as $26 \times 3 = $78 to see how close your estimate was. This helps you manage your finances effectively.
