Estimate the product by rounding nearest ten.
i. 76 x 18
ii. 84 x 57
The correct answer and explanation is:
Let’s round both numbers to the nearest ten before multiplying:
i. 76 × 18
- 76 rounded to the nearest ten is 80.
- 18 rounded to the nearest ten is 20.
Now, multiply the rounded numbers: 80×20=160080 \times 20 = 1600
So, the estimated product of 76 and 18 is 1600.
ii. 84 × 57
- 84 rounded to the nearest ten is 80.
- 57 rounded to the nearest ten is 60.
Now, multiply the rounded numbers: 80×60=480080 \times 60 = 4800
So, the estimated product of 84 and 57 is 4800.
Explanation:
Rounding numbers to the nearest ten makes the multiplication simpler, allowing for a quick estimate. By adjusting both numbers to the closest multiples of ten, the calculations become easier and faster, though less precise. This estimation method is particularly useful when you need a rough answer, such as when you’re checking the reasonableness of an answer or when doing mental math in situations where exact precision isn’t required.
After rounding, you perform the multiplication with the simpler numbers. While the results might be a little off compared to the exact product, they give you a good approximation that is easy to compute without a calculator. This method is helpful in real-life scenarios like budgeting or estimating costs, where getting a close answer quickly is more important than having perfect precision.