PSAT Math : Decimals
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Example Questions
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 #2071 : Psat Mathematics
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 #31 : 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
$3.75
$4.35
$5.10
$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 #2 : How To Add Decimals
.2
.57
2.0
.37
.47
.47
.3 can be written as .30. Now we can add the two more easily:
__________
Example Question #32 : 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 #3 : How To Add Decimals
Find the sum.
Example Question #33 : Decimals
Find the sum.
Example Question #34 : Decimals
Order the following decimals in order from least to greatest:
2.1, 6.9, 4.8, 5.2, 8.5
2.1, 4.8, 5.2, 6.9, 8.5
8.5, 6.9, 5.2, 4.8, 2.1
2.1, 5.2, 8.5, 4.8, 6.9
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.
Example Question #35 : Decimals
In the number 5,783.2935, what is the digit in the hundredths place?
The digit in the hundredths place is the one two decimal places to the right of the decimal. That digit is 9. Do not confuse the hundredths with the hundreds place, which is three spaces to the left of the decimal.
The answer is 9.
Example Question #2 : How To Order Decimals From Least To Greatest Or From Greatest To Least
Which of these decimals are the greatest?
look at the first decimal place; 0.2 and 0.201 are the largest.
0.2 = 0.200 and 0.201 > 0.200
0.201 is the greatest given decimal.
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