PSAT Math : Decimals

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #31 : Other Decimals

Round the answer to the nearest tenth.

 

Possible Answers:

Correct answer:

Explanation:

0.57 - 2.657 = -2.087

Don't forget the negative sign!

This number then rounds to -2.1.

Example Question #2 : How To Subtract Decimals

Simplify:

Possible Answers:

Correct answer:

Explanation:

Start by simplifying within the parentheses:

Then add/subtract each number

When you finish simplifying, the answer is 0.

Example Question #1 : How To Subtract Decimals

Find the difference.

Possible Answers:

Correct answer:

Explanation:

Example Question #21 : Decimals

Convert 0.0004640 into scientific notation.

Possible Answers:

The value is already in scientific notation

Correct answer:

Explanation:

When written in scientific notation, a number will follow the format in which is between one and ten and is an integer value.

To find , take the first non-zero digit in your given number as the ones place. In 0.0004640 this would be the first 4. All subsequent digits fall into the tenths, hundredths, etc. places.

To find , we must count the number of places that is removed. In 0.0004640, the first digit of  is in the ten-thousandths place. This indicates that will be .

Together, the final scientific notation will be .

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

Express 770,000,000,000 in scientific notation.

Possible Answers:

Correct answer:

Explanation:

Write the number with a decimal point and without commas:

Counting the number of places, move the decimal point to the left until it is after the first nonzero digit:

The resulting number is 7.7; the number of places the decimal point moved to the left was 11. In scientific notation, this number is .

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

Convert  into scientific notation.

Possible Answers:

Correct answer:

Explanation:

To convert a number into scientific notation, the decimal must be moved until our base number is greater than 1 and less than 10. Next, we must count the number of places we moved it and multiply it by 10 to that number. Thus, our answer is:

Example Question #511 : Arithmetic

12 grams of oxygen are equal to  atoms. Which of the following comes closest to the mass, in grams, of one million atoms of oxygen?

Possible Answers:

Correct answer:

Explanation:

In scientific notation, one million atoms is equal to  atoms. To find the mass  of this many atoms, we can solve the proportion statement

Example Question #4 : How To Convert Decimals To Scientific Notation

Define an operation  as follows:

For all real numbers 

Which of the following is equal to  ?

Possible Answers:

Correct answer:

Explanation:

Substitute and execute the operations:

Move the decimal point right five places to get it after the first nonzero digit; the scientific notation equivalent is 

Example Question #6 : How To Convert Decimals To Scientific Notation

Define an operation  as follows:

For all real numbers 

Which of the following is equal to  ?

Possible Answers:

Correct answer:

Explanation:

Substitute and execute the operations:

Move the decimal point right two places to get it after the first nonzero digit; the scientific notation equivalent is 

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

Define an operation  as follows:

For all real numbers 

Which of the following is equal to  ?

Possible Answers:

Correct answer:

Explanation:

Substitute and execute the operations:

Move the decimal point right four places to get it after the first nonzero digit; the scientific notation equivalent is 

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