HSPT Math : Decimals

Study concepts, example questions & explanations for HSPT Math

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Example Questions

Example Question #1 : Decimals

\displaystyle 1.2*.15=?

Possible Answers:

\displaystyle .18

\displaystyle 180

\displaystyle 2.7

\displaystyle 1.8

Correct answer:

\displaystyle .18

Explanation:

When multiplying decimals you ignore the decimals and multiply the two numbers like you would normally.

Then count the total number of decimal places to the right of the decimal of the original numbers.

Move the decimal from the whole number answer you just received to the left the same number of times as the total decimal places to the right of the numbers before you multiplied them.

Therefore the answer is \displaystyle .18 

 

Example Question #1 : Decimals

Divide:

\displaystyle 320 \div 0.004

Possible Answers:

\displaystyle 0.08

\displaystyle 8,000

\displaystyle 0.008

\displaystyle 80,000

\displaystyle 800

Correct answer:

\displaystyle 80,000

Explanation:

Examine the divisor 0.004. To make this a whole number, the decimal point needs to be moved three places right. Do this to both 0.004 and 320, adding an implied decimal point after the latter first:

\displaystyle 320.000 \div 0.004 \Rightarrow 320000. \div 4

Now perform this division:

\displaystyle 320,000. \div 4 = 80,000

Example Question #1 : Decimals

Evaluate: \displaystyle 0.3^{5}

Possible Answers:

\displaystyle 0.125

\displaystyle 0.0125

\displaystyle 0.00243

\displaystyle 0.000243

\displaystyle 0.0243

Correct answer:

\displaystyle 0.00243

Explanation:

\displaystyle 0.3^{5} = 0.3 \cdot 0.3\cdot 0.3\cdot 0.3\cdot 0.3

First, multiply, ignoring the decimal points:

\displaystyle 3 \cdot 3\cdot 3\cdot 3\cdot 3 = 243

Put a decimal point after the number:

\displaystyle 243.

Since there were five digits total (one per factor) left of the decimal points, move the decimal point in the product left five places, inserting zeroes as needed:

\displaystyle 0.00243

Example Question #2 : Decimals

Express 1.14 as a fraction in lowest terms.

Possible Answers:

\displaystyle \frac{114}{100}

\displaystyle \frac{1,114}{1,000}

\displaystyle \frac{57}{500}

\displaystyle \frac{57}{50}

\displaystyle \frac{57}{20}

Correct answer:

\displaystyle \frac{57}{50}

Explanation:

The fraction has its last nonzero digit in the hundredths place, so write the number, without the decimal point, over 100. Then reduce.

\displaystyle \frac{114}{100} = \frac{114\div 2}{100\div 2} = \frac{57}{50}

Example Question #105 : Arithmetic

Express 450,000,000,000 in scientific notation.

Possible Answers:

\displaystyle 4.5 \times 10^{-11}

\displaystyle 4.5 \times 10^{11}

\displaystyle 4.5 \times 10^{-12}

\displaystyle 4.5 \times 10^{12}

\displaystyle 4.5 \times 10^{10}

Correct answer:

\displaystyle 4.5 \times 10^{11}

Explanation:

To rewrite a very large number in scientific notation:

Write the number with the decimal point after it (it is implied to be at that location).

\displaystyle 450,000,000,000.

Move the decimal point left as many places as needed until it follows the first nonzero digit, which here is the four. Count the number of places it is moved - here it will be eleven places.

The number formed is \displaystyle 4.5, which will be placed in front; 11, the number of places counted, will be the exponent. The number, in scientific notation, will be \displaystyle 4.5 \times 10^{11}.

Example Question #111 : Arithmetic

\displaystyle 4.32(.78)=

Possible Answers:

\displaystyle 3.3696

\displaystyle 33.696

\displaystyle 3.96

\displaystyle 339.66

\displaystyle 33.666

Correct answer:

\displaystyle 3.3696

Explanation:

Multiply normally and remember that the decimal point is four places from the right. 

Example Question #2 : Decimals

Express  \displaystyle \frac{8}{15} as a decimal.

Possible Answers:

\displaystyle 0.5\overline{3}

\displaystyle 0.\overline{5}

\displaystyle 0.52

\displaystyle 0.5

\displaystyle 0.5\overline{8}

Correct answer:

\displaystyle 0.5\overline{3}

Explanation:

Divide 8 by 15:

 \displaystyle \frac{8}{15} = 8 \div 15 = 0.5333... 

The 3 repeats, so the correct choice is \displaystyle 0.5\overline{3}.

Example Question #3 : Decimals

Give the decimal equivalent of \displaystyle \frac{11}{18}.

Possible Answers:

\displaystyle 0.61

\displaystyle 0.\overline{611}

\displaystyle 0.611

\displaystyle 0.\overline{61}

\displaystyle 0.6\overline{1}

Correct answer:

\displaystyle 0.6\overline{1}

Explanation:

Divide 11 by 18:

\displaystyle \frac{11}{18} = 11 \div 18 = 0.61111...

The 1 repeats infinitely, so this can be rewritten as \displaystyle 0.6\overline{1}.

Example Question #3 : Decimals

Give the decimal equivalent of \displaystyle \frac{5}{27}.

Possible Answers:

\displaystyle 0.185

\displaystyle 0.186

\displaystyle 0.18\overline{5}

\displaystyle 0.\overline{185}

\displaystyle 0.1\overline{85}

Correct answer:

\displaystyle 0.\overline{185}

Explanation:

Divide 5 by 27:

\displaystyle \frac{5}{27} = 5 \div 27 = 0.185185185...

The group "185" repeats infinitely, so this can be written as \displaystyle 0.\overline{185}.

Example Question #4 : How To Find The Decimal Equivalent Of A Fraction

Give the decimal equivalent of \displaystyle \frac{7}{36}.

Possible Answers:

\displaystyle 0.\overline{19}

\displaystyle 0.19\overline{4}

\displaystyle 0.195

\displaystyle 0.19

\displaystyle 0.194

Correct answer:

\displaystyle 0.19\overline{4}

Explanation:

Divide 7 by 36: 

\displaystyle \frac{7}{36} = 7 \div 36 = 0.19444444...

The 4 repeats infinitely, so this can be rewritten as \displaystyle 0.19\overline{4}.

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