HSPT Quantitative : How to manipulate numbers

Study concepts, example questions & explanations for HSPT Quantitative

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Example Questions

Example Question #1 : How To Manipulate Numbers

What number is the square of 4 divided by 2?

Possible Answers:

\dpi{100} 1\(\displaystyle \dpi{100} 1\)

\dpi{100} 16\(\displaystyle \dpi{100} 16\)

\dpi{100} 8\(\displaystyle \dpi{100} 8\)

\dpi{100} 4\(\displaystyle \dpi{100} 4\)

Correct answer:

\dpi{100} 8\(\displaystyle \dpi{100} 8\)

Explanation:

First, square 4.

\dpi{100} 4^{2}=16\(\displaystyle \dpi{100} 4^{2}=16\)

Then divide the answer by two.

\dpi{100} \frac{16}{2}=8\(\displaystyle \dpi{100} \frac{16}{2}=8\)

Example Question #2 : How To Manipulate Numbers

What number is the cube of 4 multiplied by 2?

Possible Answers:

\dpi{100} 32\(\displaystyle \dpi{100} 32\)

\dpi{100} 24\(\displaystyle \dpi{100} 24\)

\dpi{100} 128\(\displaystyle \dpi{100} 128\)

\dpi{100} 64\(\displaystyle \dpi{100} 64\)

Correct answer:

\dpi{100} 128\(\displaystyle \dpi{100} 128\)

Explanation:

First, cube 4.

\dpi{100} 4^{3}=64\(\displaystyle \dpi{100} 4^{3}=64\)

Multiply that answer by 2.

\dpi{100} 2\times 64=128\(\displaystyle \dpi{100} 2\times 64=128\)

Example Question #1 : Number Manipulation*

What number divided by 5 is \dpi{100} \frac{1}{8}\(\displaystyle \dpi{100} \frac{1}{8}\) of 40?

Possible Answers:

\dpi{100} 25\(\displaystyle \dpi{100} 25\)

\dpi{100} 40\(\displaystyle \dpi{100} 40\)

\dpi{100} 5\(\displaystyle \dpi{100} 5\)

\dpi{100} 20\(\displaystyle \dpi{100} 20\)

Correct answer:

\dpi{100} 25\(\displaystyle \dpi{100} 25\)

Explanation:

Set up an equation that fits the information:

\dpi{100} \frac{x}{5}=\frac{1}{8}\cdot 40\(\displaystyle \dpi{100} \frac{x}{5}=\frac{1}{8}\cdot 40\)

\dpi{100} \frac{x}{5}=5\(\displaystyle \dpi{100} \frac{x}{5}=5\)

\dpi{100} 5\cdot \frac{x}{5}=5\cdot 5\(\displaystyle \dpi{100} 5\cdot \frac{x}{5}=5\cdot 5\)

\dpi{100} x=25\(\displaystyle \dpi{100} x=25\)

Example Question #3 : How To Manipulate Numbers

What number is 4 times \dpi{100} \frac{1}{8}\(\displaystyle \dpi{100} \frac{1}{8}\) of 80?

Possible Answers:

\dpi{100} 20\(\displaystyle \dpi{100} 20\)

\dpi{100} 32\(\displaystyle \dpi{100} 32\)

\dpi{100} 3200\(\displaystyle \dpi{100} 3200\)

\dpi{100} 40\(\displaystyle \dpi{100} 40\)

Correct answer:

\dpi{100} 40\(\displaystyle \dpi{100} 40\)

Explanation:

Set up an equation using the information provided, and then solve.

\dpi{100} x=4\cdot (\frac{1}{8}\cdot 80)\(\displaystyle \dpi{100} x=4\cdot (\frac{1}{8}\cdot 80)\)

\dpi{100} x=4\cdot 10\(\displaystyle \dpi{100} x=4\cdot 10\)

\dpi{100} x=40\(\displaystyle \dpi{100} x=40\)

Example Question #2 : Number Manipulation*

What number divided by \(\displaystyle 2\) is \(\displaystyle 150\) percent of \(\displaystyle 60\)?

Possible Answers:

\(\displaystyle 90\)

\(\displaystyle 180\)

\(\displaystyle 85\)

\(\displaystyle 45\)

Correct answer:

\(\displaystyle 180\)

Explanation:

Work backwards to solve this problem. First, \(\displaystyle 150\) percent of \(\displaystyle 60\) is \(\displaystyle 90\), because \(\displaystyle 1.50\cdot 60=90\).

Now, multiply this by \(\displaystyle 2\) to reverse the division.

\(\displaystyle 90\cdot 2=180\), so the answer is 180.

Example Question #6 : How To Manipulate Numbers

\(\displaystyle 72\) is \(\displaystyle 30\) percent of what number?

Possible Answers:

\(\displaystyle 216\)

\(\displaystyle 240\)

\(\displaystyle 360\)

\(\displaystyle 22\)

Correct answer:

\(\displaystyle 240\)

Explanation:

Using \(\displaystyle z\) to represent the unknown number, we know that \(\displaystyle .30z=72\). Using algebraic manipulation, divide both sides by \(\displaystyle .30\) to find \(\displaystyle z\).

\(\displaystyle 72\div .30=240\)

Example Question #7 : How To Manipulate Numbers

What number is  \(\displaystyle \frac{2}{3}\) of \(\displaystyle 5\) less than \(\displaystyle 101\)?

Possible Answers:

\(\displaystyle 64\)

\(\displaystyle 71\)

\(\displaystyle 96\)

\(\displaystyle 60\)

Correct answer:

\(\displaystyle 64\)

Explanation:

Work backwards to solve this problem. First, \(\displaystyle 5\) less than \(\displaystyle 101\) is \(\displaystyle 96\):

\(\displaystyle 101-5=96\)

Then, \(\displaystyle \frac{2}{3}\) of \(\displaystyle 96\) is \(\displaystyle 64\):

\(\displaystyle 96\cdot\frac{2}{3}=64\)

Example Question #8 : How To Manipulate Numbers

What number is \(\displaystyle 35\) percent of the difference between \(\displaystyle 153\) and \(\displaystyle 113\)?

Possible Answers:

\(\displaystyle 114\)

\(\displaystyle 54\)

\(\displaystyle 14\)

\(\displaystyle 40\)

Correct answer:

\(\displaystyle 14\)

Explanation:

Work backwards to solve this problem. First, the difference between \(\displaystyle 153\) and \(\displaystyle 113\) is \(\displaystyle 40\):

\(\displaystyle 153-113=40\)

Then, \(\displaystyle 35\) percent of that is \(\displaystyle 14\):

\(\displaystyle 40\cdot.35=14\)

Example Question #6 : How To Manipulate Numbers

What number is \(\displaystyle 28\) percent of \(\displaystyle 225\)?

Possible Answers:

\(\displaystyle 72\)

\(\displaystyle 63\)

\(\displaystyle 54\)

\(\displaystyle 900\)

Correct answer:

\(\displaystyle 63\)

Explanation:

Multiply \(\displaystyle 225\) by \(\displaystyle .28\) to find \(\displaystyle 28\) percent:

\(\displaystyle 225\cdot.28=63\)

Example Question #3 : How To Manipulate Numbers

What is the average of \(\displaystyle 9^{2}\) and \(\displaystyle 11^{2}\)?

Possible Answers:

\(\displaystyle 92\)

\(\displaystyle 202\)

\(\displaystyle 101\)

\(\displaystyle 104\)

Correct answer:

\(\displaystyle 101\)

Explanation:

The first step is to calculate the squares:

\(\displaystyle 9^2=9\cdot9=81\)

\(\displaystyle 11^2=11\cdot11=121\)

Second, find the average by finding the sum and dividing by the number of numbers:

\(\displaystyle \frac{81+121}{2}=\frac{202}{2}=101\)

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