PSAT Math : PSAT Mathematics

Study concepts, example questions & explanations for PSAT Math

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Example Questions

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 

Example Question #5 : How To Convert Decimals To Scientific Notation

Represent  in scientific notation.

Possible Answers:

Correct answer:

Explanation:

Trick: Count how many times you move the decimal to get 3.452.  We moved the decimal 6 times to the right so the exponent above 10 will be -6.  If we move the decimal to the left then our exponent would be positive.

Another way to remember whether the exponent will be negative or possitive is whether or not the original number is less than or greater than one. If the original number is less than one, when you put it in scientific notation the exponent above the 10 will be negative. On the other hand, if the original number is greater than one, then the exponent above the 10 will be positive.

Example Question #2071 : Psat Mathematics

 can be represented by which of the following notations?

Possible Answers:

 

 

Correct answer:

Explanation:

In order to convert the decimal to scientific notation, count the number of spaces from the decimal point to the space between the 4 and the 6 (scientific notation requires that the leftmost number be a number between 1 and 10). In this instance it is 3 spaces. Since the decimal point will be moving from left to right, we know that our exponent will be negative, and in this case -3.

 then becomes  X .

Example Question #1 : How To Add Decimals

If Johnny buys two comic books, priced at $1.50 each, and a candy bar, priced at $0.75, he'll have three quarters and two dimes left over.  How much money does he have right now?

Possible Answers:

$3.20

$4.35

$5.10

$4.70

$3.75

Correct answer:

$4.70

Explanation:

Add what he can purchase to what he has left over:

Two comic books and the candy bar: $1.50 + $1.0 + $0.75 = $3.75

Three quarters and two dimes: $0.75 + $0.20 = $0.95

Therefore his total amount of money is $3.75 + $0.95 = $4.70.

Example Question #2 : How To Add Decimals

Possible Answers:

.2

.57

2.0

.37

.47

Correct answer:

.47

Explanation:

.3 can be written as .30. Now we can add the two more easily:

    

__________

    

 

Example Question #32 : Decimals

Menu

Above is the menu at a coffee shop.

Delia has a coupon that entitles her to a free butter croissant with the purchase of one large drink of any kind. The coupon says "limit one per coupon".

She decides to purchase two small espressos, two small cappucinos, and four butter croissants. Disregarding tax, how much will Delia spend?

Possible Answers:

Correct answer:

Explanation:

Delia will not use the coupon, since all four of her drinks are small. She will pay full price for:

Two small espressos: 

Two small cappucinos: 

Four butter croissants: 

The total price: 

Example Question #3 : How To Add Decimals

Find the sum.

Possible Answers:

Correct answer:

Explanation:

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