SAT Math : Basic Squaring / Square Roots

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #1 : Basic Squaring / Square Roots

If all real values of x\(\displaystyle x\) lie between 0 and 1, which of the following is always greater than 1?

Possible Answers:

\frac{x}{10}\(\displaystyle \frac{x}{10}\)

x+1\(\displaystyle x+1\)

x^{4}\(\displaystyle x^{4}\)

x^{2}\(\displaystyle x^{2}\)

5x^{2}\(\displaystyle 5x^{2}\)

Correct answer:

x+1\(\displaystyle x+1\)

Explanation:

If x\(\displaystyle x\) is greater than 0, then adding 1 to x\(\displaystyle x\) will make it greater than 1. Taking a number between 0 and 1 to a power results in a smaller number.

Example Question #2 : Basic Squaring / Square Roots

Evaluate:

0.082

Possible Answers:

0.00064

0.0064

0.64

0.064

0.00064

Correct answer:

0.0064

Explanation:

0.08 * 0.08

First square 8:

8 * 8 = 64

Then move the decimal four places to the left:

0.0064

Example Question #1 : How To Find The Square Root Of A Decimal

Find the square root of the following decimal:

\(\displaystyle \sqrt{.00081}=\)

Possible Answers:

\(\displaystyle 0.9\)

\(\displaystyle 0.09\)

\(\displaystyle 0.009\)

\(\displaystyle 0.028\)

\(\displaystyle 90\)

Correct answer:

\(\displaystyle 0.028\)

Explanation:

The easiest way to find the square root of a fraction is to convert it into scientific notation. 

\dpi{100} \small .00081 = 8.1 \times 10^{-4}\(\displaystyle \dpi{100} \small .00081 = 8.1 \times 10^{-4}\)

The key is that the exponent in scientific notation has to be even for a square root because the square root of an exponent is diving it by two. The square root of 9 is 3, so the square root of 8.1 is a little bit less than 3, around 2.8

 \dpi{100} \small \sqrt{8.1 \times 10^{-4}} \approx 2.8 \times 10^{-2} \approx 0.028\(\displaystyle \dpi{100} \small \sqrt{8.1 \times 10^{-4}} \approx 2.8 \times 10^{-2} \approx 0.028\)

Example Question #1 : Basic Squaring / Square Roots

Find the square root of the following decimal:

\(\displaystyle \small \sqrt{0.0049}\)

Possible Answers:

\(\displaystyle \small 0.7\)

\(\displaystyle \small 0.022\)

\(\displaystyle \small 0.007\)

\(\displaystyle \small 0.07\)

Correct answer:

\(\displaystyle \small 0.07\)

Explanation:

To find the square root of this decimal we convert it into scientific notation.

\(\displaystyle \small 0.0049 = 49 \cdot10^{-4}\)

Because \(\displaystyle \small 10^{-4}\) has an even exponent, we can divide the exponenet by 2 to get its square root.

\(\displaystyle \small \sqrt{0.0049} = \sqrt{49}\cdot\sqrt{10^{-4}} = 7\cdot10^{-2} = 0.07\)

Example Question #1 : How To Find The Square Root Of A Decimal

Find the square root of the following decimal:

\(\displaystyle \small \sqrt{0.025}\)

Possible Answers:

\(\displaystyle \small 0.625\)

\(\displaystyle \small 0.158\)

\(\displaystyle \small 0.05\)

\(\displaystyle \small 0.005\)

Correct answer:

\(\displaystyle \small 0.158\)

Explanation:

This problem can be solve more easily by rewriting the decimal into scientific notation.

\(\displaystyle \small 0.025 = 2.5 \times 10^{-2}\)

Because \(\displaystyle \small 10^{-2}\) has an even exponent, we can take the square root of it by dividing it by 2. The square root of 4 is 2, and the square root of 1 is 1, so the square root of 2.5 is less than 2 and greater than 1.

\(\displaystyle \small \sqrt{0.025} = \sqrt{2.5}\times \sqrt{10^{-2}} = 1.58\times 10^{-1} = 0.158\)

Example Question #3 : Basic Squaring / Square Roots

Find the square root of the following decimal:

\(\displaystyle \small \sqrt{0.00036}\)

Possible Answers:

\(\displaystyle \small 0.019\)

\(\displaystyle \small 0.013\)

\(\displaystyle \small 0.06\)

\(\displaystyle \small 0.006\)

Correct answer:

\(\displaystyle \small 0.019\)

Explanation:

This problem becomes much simpler if we rewrite the decimal in scientific notation

\(\displaystyle \small 0.00036 = 3.6\times 10^{-4}\)

Because \(\displaystyle \small 10^{-4}\) has an even exponent, we can take its square root by dividing it by two. The square root of 4 is 2, and because 3.6 is a little smaller than 4, its square root is a little smaller than 2, around 1.9

\(\displaystyle \small \sqrt{0.025} = \sqrt{3.6}\times \sqrt{10^{-4}} \approx 1.9\times 10^{-2} = 0.019\)

Example Question #2 : Basic Squaring / Square Roots

Find the square root of the following decimal:

\(\displaystyle \small \sqrt{0.00064}\)

Possible Answers:

\(\displaystyle \small 0.8\)

\(\displaystyle \small 0.008\)

\(\displaystyle \small 0.08\)

\(\displaystyle \small 0.0253\)

Correct answer:

\(\displaystyle \small 0.0253\)

Explanation:

To find the square root of this decimal we convert it into scientific notation.

\(\displaystyle \small \small 0.00064 = 6.4 \times10^{-4}\)

Because \(\displaystyle \small 10^{-4}\) has an even exponent, we can divide the exponenet by 2 to get its square root. The square root of 9 is 3, and the square root of 4 is two, so the square root of 6.4 is between 3 and 2, around 2.53

\(\displaystyle \small \small \sqrt{0.00064} = \sqrt{6.4}\times\sqrt{10^{-4}} \approx 2.53 \times10^{-2} = 0.0253\)

Example Question #5 : How To Find The Square Root Of A Decimal

Find the square root of the following decimal:

\(\displaystyle \small \sqrt{0.0169}\)

Possible Answers:

\(\displaystyle \small 0.0285\)

\(\displaystyle \small 0.0411\)

\(\displaystyle \small 0.13\)

\(\displaystyle \small \small 0.0318\)

Correct answer:

\(\displaystyle \small 0.13\)

Explanation:

To find the square root of this decimal we convert it into scientific notation.

\(\displaystyle \small \small 0.0169 = 169\times10^{-4}\)

Because \(\displaystyle \small 10^{-4}\) has an even exponent, we can divide the exponenet by 2 to get its square root. \(\displaystyle \small 169\) is a perfect square, whose square root is \(\displaystyle \small 13\).

\(\displaystyle \small \small \sqrt{0.0169} = \sqrt{169}\times \sqrt{10^{-4}} =13\times10^{-2} = 0.13\)

Example Question #6 : How To Find The Square Root Of A Decimal

Find the square root of the following decimal:

\(\displaystyle \small \sqrt{0.00001}\)

Possible Answers:

\(\displaystyle \small 0.0001\)

\(\displaystyle \small 0.001\)

\(\displaystyle \small 0.00316\)

\(\displaystyle \small 0.01\)

Correct answer:

\(\displaystyle \small 0.00316\)

Explanation:

To find the square root of this decimal we convert it into scientific notation.

\(\displaystyle \small \small \small 0.00001 = 10 \times10^{-6}\)

Because \(\displaystyle \small \small 10^{-6}\) has an even exponent, we can divide the exponenet by 2 to get its square root. The square root of 9 is 3, so the square root of 10 should be a little larger than 3, around 3.16

\(\displaystyle \small \small \sqrt{0.00001} = \sqrt{10}\times \sqrt{10^{-6}} = 3.16\times10^{-3} = 0.00316\)

Example Question #32 : Decimals

Find the square root of the following decimal:

\(\displaystyle \small \sqrt{0.004}\)

Possible Answers:

\(\displaystyle \small 0.0632\)

\(\displaystyle \small 0.02\)

\(\displaystyle \small 0.002\)

\(\displaystyle \small 0.016\)

Correct answer:

\(\displaystyle \small 0.0632\)

Explanation:

To find the square root of this decimal we convert it into scientific notation.

\(\displaystyle \small \small 0.004 = 40 \times10^{-4}\)

Because \(\displaystyle \small 10^{-4}\) has an even exponent, we can divide the exponenet by 2 to get its square root. The square root of 36 is 6, so the square root of 40 should be a little more than 6, around 6.32. 

\(\displaystyle \small \small \small \sqrt{0.004} = \sqrt{40}\times\sqrt{10^{-4}} \approx 6.32 \times10^{-2} = 0.0632\)

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