Mathematics
Grade5
Easy
Question
Estimate the product 838 × 39.
- 30,000
- 28,000
- 32,000
- 33,000
Hint:
The estimate math definition in a quick guess that is close enough to work with but is not necessarily accurate. Estimating products by rounding numbers to the nearest ten, hundred, thousand etc., we know how to estimate the sum, difference, etc., to the nearest 10, 100, 1000, etc. Now we have to estimate the products.
The correct answer is: 32,000
To estimate the product, we first round off the multiplier and the multiplicand to the nearest tens, hundreds, or thousands and then multiply the rounded numbers.
Estimate the product: 838 x 39
838 x 39 (39 is rounded up to 40,838 is rounded down to 800)
One number is rounded up and the other is rounded down. Here 39 is rounded up to the nearest tens, ie..40, while 838 is rounded down to the nearest hundreds, ie..800
=40 x 800
=32000
estimated product of 800 x 40= 32,000
Or,
Rounding 838 so that it has only one non-zero digit is rounding it to nearest hundred.
838 rounds to nearest hundred as 800 as tens digit 4 < 5.
Step 2:
Rounding 39 so that it has only one non-zero digit is rounding it to nearest ten.
39 rounds to nearest ten as 40 as one’s digit 8 > 5.
Step 3:
So the estimated product after rounding each number so that it has only one non-zero digit is
800 × 40 = 32000.
Estimating products hop us to check the reasonableness of an answer. The definition of an estimate is an opinion or a guess of the size, worth or cost of something. An example of an estimate is a list of times and charges that it may cost to complete a construction job.
