PSAT Math : Decimal Operations
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Example Question #6 : How To Convert Decimals To Scientific Notation
Define an operation 
For all real numbers 
Which of the following is equal to 
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 #4 : How To Convert Decimals To Scientific Notation
Define an operation
For all real numbers 
Which of the following is equal to 
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 
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 #21 : Decimal Operations
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.
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?
$3.20
$5.10
$3.75
$4.35
$4.70
$4.70
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 #1 : How To Add Decimals
2.0
.57
.47
.2
.37
.47
.3 can be written as .30. Now we can add the two more easily:
__________
Example Question #2 : How To Add Decimals
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?
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 #2 : How To Add Decimals
Find the sum.
Example Question #3 : How To Add Decimals
Find the sum.
Example Question #1 : How To Order Decimals From Least To Greatest Or From Greatest To Least
Order the following decimals in order from least to greatest:
2.1, 6.9, 4.8, 5.2, 8.5
8.5, 6.9, 5.2, 4.8, 2.1
2.1, 5.2, 8.5, 4.8, 6.9
2.1, 4.8, 5.2, 6.9, 8.5
6.9, 4.8, 8.5, 5.2, 2.1
2.1, 4.8, 5.2, 6.9, 8.5
Look at the ones place first, ignoring the decimal. The order from greatest to least is 2, 4, 5, 6, and 8. Because none of the numbers in the ones place are the same, it doesn't matter what the decimal will be on these numbers- the order will remain the same. The order is 2.1, 4.8, 5.2, 6.9, 8.5.
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