Understanding decimals - GMAT Quantitative Reasoning

Card 0 of 10

Question

If and are positive integers such that = 4.46, which of the following numbers could be the remainder when is divided by ?

Answer

Given that

it follows that .

We don't need to know or , the only important information is that:

Where the remainder is any one of the answer choices. This is because the remainder for any divisor/dividend pair is the product of the decimal portion of the quotient and the divisor.

Since we don't know y, our answer choice for the remainder is any answer that satisfies the above equation for a positive interger, since is specified as such in the problem.

The only answer choice that satisfies the constraints on is 184:

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Question

Rewrite as a fraction in lowest terms:

Answer

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Question

Add one hundred seven ten-thousandths to seventeeen one-hundredths.

Answer

One hundred seven ten-thousandths = 0.0107

Seventeeen one-hundredths = 0.17, or 0.1700

The sum:

This is one thousand eight hundred seven ten-thousandths.

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Question

Subtract nine hundred six ten-thousandths from four tenths.

Answer

Nine hundred six ten-thousandths = 0.0906

Four tenths = 0.4, or 0.4000

The difference:

This is three thousand ninety-four ten-thousandths.

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Question

Multiply seventy-seven one-hundredths by sixty-six one-thousandths.

Answer

Seventy-seven one-hundredths = 0.77

Sixty-six one-thousandths = 0.066

The product:

0.77 and 0.066 have a total of five digits to the right of their decimal points, so position the decimal point in the answer so that there are five digits to its right.

This is five thousand eighty-two hundred-thousandths.

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Question

Divide eight hundred eighty-eight thousandths by sixty-four ten-thousandths.

Answer

Eight hundred eighty-eight thousandths = 0.888

Sixty-four ten-thousandths = 0.0064

Set up a long division:

Division

Move the decimal point four places right in both numbers so that the divisor will be a whole number. Note that this will require the use of placeholder zeroes in the dividend.

Division

(Note that leading zeroes have been removed.)

Carry out the long division, making sure you align the decimals:

Division

The quotient of this division is that of the original problem, so the correct choice is 138.75.

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Question

Which of the following is the square of twenty seven one-thousandths?

Answer

Twenty-seven one-thousandths = 0.027

Its square is

Multiply without regard to the decimals first:

0.027 and 0.027 have a total of six digits to the right of their decimal points, so position the decimal point in the answer so that there are six digits to its right.

This is seven hundred twenty-nine one-millionths.

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Question

Which of the following is the cube of fifteen one-hundredths?

Answer

Fifteen one-hundredths = 0.15

Its cube is

Multiply without regard to the decimals first:

0.15, 0.15, and 0.15 have a total of six digits to the right of their decimal points, so position the decimal point in the answer so that there are six digits to its right.

This is three thousand three hundred seventy-five one-millionths.

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Question

Which of these equations is not correct?

Answer

Although tempting, a calculator is not required to spot the correct answer.

is equal to as it is parts of . And therefore must be slightly different. (It's it actually )

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Question

If we divide 10 by 3, what is the 10th digit after the decimal point of the quotient?

Answer

The tenth digit after the decimal point is 3.

When dividing 1 by 3 or 10 by 3, we get repeating 3s. So, there must be a 3 in the tenths digit.

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