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Key Takeaway
Estimation Rule of Thumb
General rule for product estimation.
To estimate the product, round off each factor to its greatest place, then multiply the rounded off factors.
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Student can round numbers and use them to quickly estimate sums, differences, and products.
General rule for product estimation.
Real-world scenarios for estimation.
Imagine Rohan is planning a treat for his eight friends on his birthday. His father gave him ₹ 500 for this special occasion.
Showing how rounding to the wrong place ruins estimation.
Problem. Estimate the difference: .
Applying the rule of greatest place rounding.
Let us look at a worked example to estimate the product of 52 and 786.
To estimate this product efficiently, we first need to round off each factor to its greatest place. For the first number, 52 can be rounded off to the nearest ten as .
For the second number, 786 can be rounded off to the nearest hundred as . Now that we have our rounded factors, we multiply them together to get a quick approximation.
Hence, the estimated product is calculated as 50 × 800, which gives us an estimated product of . This method provides a quick and reasonable guess of the actual value.
Multiple choice estimation from Worksheet 7 and 8.
Estimate the difference: .