GRE Math : How to convert decimals to scientific notation

Study concepts, example questions & explanations for GRE Math

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Example Questions

Example Question #1 : How To Convert Decimals To Scientific Notation

Write  in scientific notation.

Possible Answers:

Correct answer:

Explanation:

We want to move the decimal point to the place just after the first non-zero number, in this case 6, and then drop all of the non-significant zeros. We need to move the decimal point five spaces to the right, so our exponent should be negative.  If the decimal had moved left, we would have had a positive exponent.  

In this case we get 6.009 * 105.

Example Question #1364 : Act Math

 is equal to which of the following?

Possible Answers:

Correct answer:

Explanation:

We need to convert  into a number of the form .

The trick is, however, figuring out what  should be. When you have to move your decimal point to the right, you need to make the decimal negative. (Note, though, when you multiply by a negative decimal, you move to the left. We are thinking in "reverse" because we are converting.)

Therefore, for our value, . So, our value is:

Example Question #1 : Other Decimals

 is equal to which of the following?

Possible Answers:

Correct answer:

Explanation:

The easiest way to do this is to convert each of your answer choices into scientific notion and compare it to .

For each of the answer choices, this would give us:

 (Which is, thus, the answer.)

When you convert, you add for each place that you move to the left and subtract for each place you move to the right. (Note that this is opposite of what you do when you multiply out the answer. We are thinking in "reverse" because we are converting.)

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