9514 1404 393
Answer:
- B
- A, E
- D
Explanation:
Yes, it is very important. The idea here is that the decimal point in division problems like these can be moved the same number of places in the same direction in each number without changing the result.
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1. Without a calculator, this is about 8/5, which you know to be more than 1 and less than 4. The only suitable answer choice is the correct one:
B 1.645 ft.
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2. Moving the decimal point 1 place to the left in both numbers, we have ...
(892×10) ÷ (8×10) = 8290 ÷ 80 . . . . matches A
Moving the decimal point 3 places to the left in both numbers, we have ...
(892×0.001) ÷ (8×0.001) = 0.892 ÷ 0.008 . . . . matches E
The other choices did something other than move the decimal point the same number of places. (Your calculator can verify this.)
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3. Moving the decimal point 3 places to the right, we have ...
(4367×1000) ÷ (0.004×1000) = 4,367,000 ÷ 4 ≈ 1,000,000
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Additional comment
For numbers like the ones in problem 3 that differ substantially in magnitude, it can work well to adjust the decimal points in both numbers so the divisor is between 1 and 10. This lets you easily estimate the position of the decimal point in the quotient.
Of course, if you're doing long division by hand, you always adjust the decimal points so the divisor is an integer (possibly with no trailing zeros).