Lesson 5 of 13
A good estimate is fast and close
Show on a big screenLook quickly at three price tags. About ₹500? You did not add exactly.
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Step 1 of 4
- Three prices: ₹186, ₹243, ₹95.
- Round each to the nearest hundred: ₹200, ₹200, ₹100.
- Add the rounded prices: ₹500.
- Real total: ₹524. Close!
The rule
Yes, ₹500 is close to the real total.
An estimate is a fast answer close to the real one. Round each number first: change it to a near, easy number. Then add the rounded numbers.
Rounding to the nearest ten is slower. Rounding to tens changes each number by less. So the answer is usually closer.
Example
₹167 + ₹154 is really ₹321. Round to hundreds: ₹167 and ₹154 both become ₹200. 200 + 200 = 400. Round to tens: ₹167 becomes ₹170 and ₹154 becomes ₹150. 170 + 150 = 320. The real total is ₹321. So ₹320 is much closer than ₹400.
Try the lab to finish this lesson.