How to add and subtract decimals - HSPT Math
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Jenny is getting ready for school. She bought school supplies on a tax-free day. She bought notebooks for $1.25 each and crayons for $0.90 each. Jenny bought two more notebooks than crayons. She paid with a ten dollar bill and got $1.05 in change. How many notebooks did she buy?
Jenny is getting ready for school. She bought school supplies on a tax-free day. She bought notebooks for $1.25 each and crayons for $0.90 each. Jenny bought two more notebooks than crayons. She paid with a ten dollar bill and got $1.05 in change. How many notebooks did she buy?
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Define variables as x = number of crayons and x + 2 = number of notebooks
To find out how much she spent, we subtract her change from what she paid with: 10.00 – 1.05 = 8.95
Then we need to solve the problem cost of notebooks plus the cost of crayons equals the total cost.
1.25(x + 2) + 0.90x = 8.95 and solving for x gives 3 crayons and 5 notebooks
Define variables as x = number of crayons and x + 2 = number of notebooks
To find out how much she spent, we subtract her change from what she paid with: 10.00 – 1.05 = 8.95
Then we need to solve the problem cost of notebooks plus the cost of crayons equals the total cost.
1.25(x + 2) + 0.90x = 8.95 and solving for x gives 3 crayons and 5 notebooks
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A runner runs 10.2 miles east, then 2.3 miles west, then 1.4 miles east.
How many miles did the runner travel from where he started? (How far east did the runner go)?
A runner runs 10.2 miles east, then 2.3 miles west, then 1.4 miles east.
How many miles did the runner travel from where he started? (How far east did the runner go)?
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When the runner is travelling east, it's in the positive direction. West is the negative direction. So we can compute it by doing the operation 10.2 + (–2.3) + 1.4 = 9.3
When the runner is travelling east, it's in the positive direction. West is the negative direction. So we can compute it by doing the operation 10.2 + (–2.3) + 1.4 = 9.3
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If Susie bought a pair of shoes for 
, a shirt for 
, and a pair of pants for 
. How much did she spend in total?
If Susie bought a pair of shoes for
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You add all three values and you get 
.
You add all three values and you get
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The menu of a local coffeehouse reads as follows:
Sandy orders some drinks for herself and some friends. She orders three cappuccinos, two iced teas, two cafe lattes, and an espresso. The sales tax is five percent. How much change does she receive back for a twenty-dollar bill?
The menu of a local coffeehouse reads as follows:
Sandy orders some drinks for herself and some friends. She orders three cappuccinos, two iced teas, two cafe lattes, and an espresso. The sales tax is five percent. How much change does she receive back for a twenty-dollar bill?
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The three cappuccinos cost: 
The two iced teas cost 
The two cafe lattes cost 
The espresso costs 
.
Add these amounts to get the cost before tax:
The tax is five percent of 
or:
Add both values in order to obtain the total cost after tax.
As a result, the change from a twenty-dollar bill is as follows:
The three cappuccinos cost:
The two iced teas cost
The two cafe lattes cost
The espresso costs
Add these amounts to get the cost before tax:
The tax is five percent of
Add both values in order to obtain the total cost after tax.
As a result, the change from a twenty-dollar bill is as follows:
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What is 
?
What is
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removed from 
results in the whole integer 
.
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Subtract: 
Subtract:
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Rewrite 
adding the correct number of placeholders and evaluate.
Rewrite
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Define an operation 
on the set of positive integers as follows:
If 
, then which of the following could 
not be equal to?
Define an operation
If
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If 
, then the greatest common factor of 
and 20 is 10. 80 and 20 both have 20 as a factor - 20 is its own factor, since 
, and 20 is a factor of 80, since 
. Therefore, 10 is not the greatest common factor of 20 and 80, and 80 is the correct choice.
Of the other three factors, it can be seen that the GCF of 20 and each individual number is 10 by looking at each prime factorization:
In each pairing, the common prime factors are 2 and 5, so the GCF is 
.
If
Of the other three factors, it can be seen that the GCF of 20 and each individual number is 10 by looking at each prime factorization:
In each pairing, the common prime factors are 2 and 5, so the GCF is
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Above is the menu at the concession stand at a school carnival. Ken wants to purchase a hamburger, a medium order of fries, and medium soda for himself, and a hot dog, a small order of fries, and a small soda for his friend Donna. He hands the clerk a $10 bill and a $5 bill. He has some $1 bills in his pocket; how many of them will he need to hand to the clerk along with the other two bills?
(No tax is charged, since this is a school event)
Above is the menu at the concession stand at a school carnival. Ken wants to purchase a hamburger, a medium order of fries, and medium soda for himself, and a hot dog, a small order of fries, and a small soda for his friend Donna. He hands the clerk a $10 bill and a $5 bill. He has some $1 bills in his pocket; how many of them will he need to hand to the clerk along with the other two bills?
(No tax is charged, since this is a school event)
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The items Ken purchases are as follows:
Hamburger: $4.89
Medium fries: $2.79
Medium soda: $1.69
Hot dog: $4.39
Small fries: $2.29
Small soda: $1.09
The sum of the prices of these items:
Subtract from $20:
Rounding this up - Ken needs to give the clerk three more $1 bills.
The items Ken purchases are as follows:
Hamburger: $4.89
Medium fries: $2.79
Medium soda: $1.69
Hot dog: $4.39
Small fries: $2.29
Small soda: $1.09
The sum of the prices of these items:
Subtract from $20:
Rounding this up - Ken needs to give the clerk three more $1 bills.
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The above is a menu at the concession stand at a drive-in movie.
Gary wants to order two hamburgers and two small orders of fries. He wants to order two sodas of the same size. If he has just a twenty-dollar bill on hand, what is the largest size soda of which he can order two?
The above is a menu at the concession stand at a drive-in movie.
Gary wants to order two hamburgers and two small orders of fries. He wants to order two sodas of the same size. If he has just a twenty-dollar bill on hand, what is the largest size soda of which he can order two?
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The easiest way to think of this is to note that Gary seems to be ordering for two people, himself and a friend. He has $20, so half of this will be for himself and half for his friend - and half of $20 is $10.
Each hamburger costs $4.89, and each small order of fries costs $2.29. This leaves
to spend on a soda for each person. This will enable to him to buy both himself and his friend a large soda.
The easiest way to think of this is to note that Gary seems to be ordering for two people, himself and a friend. He has $20, so half of this will be for himself and half for his friend - and half of $20 is $10.
Each hamburger costs $4.89, and each small order of fries costs $2.29. This leaves
to spend on a soda for each person. This will enable to him to buy both himself and his friend a large soda.
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The above is a menu at the concession stand at a drive-in movie. The stand also offers a special "Meal Deal": a hamburger or a hot dog, a medium order of fries, and a medium soda for 
.
Randy orders two Meal Deals - a hamburger Meal Deal for himself and a hot dog Meal Deal for his friend Denise. How much more would he have paid for the items separately?
(Ignore tax)
The above is a menu at the concession stand at a drive-in movie. The stand also offers a special "Meal Deal": a hamburger or a hot dog, a medium order of fries, and a medium soda for
Randy orders two Meal Deals - a hamburger Meal Deal for himself and a hot dog Meal Deal for his friend Denise. How much more would he have paid for the items separately?
(Ignore tax)
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The two Meal Deals cost 
.
Purchased separately, the hamburger would have cost $4.89; the hot dog, $4.39; each of the two medium orders of fries, $2.79; and each of the two medium sodas, $1.69. The total price of the items, purchased separately, would have been
The difference between this and the $16 paid for the food is
The two Meal Deals cost
Purchased separately, the hamburger would have cost $4.89; the hot dog, $4.39; each of the two medium orders of fries, $2.79; and each of the two medium sodas, $1.69. The total price of the items, purchased separately, would have been
The difference between this and the $16 paid for the food is
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The above is a menu at the concession stand at a drive-in movie. The stand also offers a Family Chicken Strip Bucket - twenty chicken strips, four medium orders of fries, and four medium sodas for $30.
How much more would the items of the Family Chicken Strip Bucket cost if they were purchased separately?
(Ignore tax)
The above is a menu at the concession stand at a drive-in movie. The stand also offers a Family Chicken Strip Bucket - twenty chicken strips, four medium orders of fries, and four medium sodas for $30.
How much more would the items of the Family Chicken Strip Bucket cost if they were purchased separately?
(Ignore tax)
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There are twenty chicken strips in the Family Chicken Strip Bucket, which are the same as in five orders; each order costs $3.99 separately. Each medium order of fries costs $2.79 separately, and each medium soda costs $1.69 separately. The items separately cost a total of
Subtract $30; the savings amount to
There are twenty chicken strips in the Family Chicken Strip Bucket, which are the same as in five orders; each order costs $3.99 separately. Each medium order of fries costs $2.79 separately, and each medium soda costs $1.69 separately. The items separately cost a total of
Subtract $30; the savings amount to
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What is 16.7548 rounded to the nearest tenth?
What is 16.7548 rounded to the nearest tenth?
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The tenth's place is the position one unit to the right of the decimal point. In this case, that is the 7.
After identifying the position, we need to determine if this number remains 7 or if we need to round it up to 8. If the number to the right of the tenth's place is 4 or lower, then our number will remain 7. If it is 5 or greater, then we will round the 7 up to 8.
In this case, the number is indeed 5, so our tenth's place becomes 8. All numbers to the left of the tenth's place will remain the same.
The tenth's place is the position one unit to the right of the decimal point. In this case, that is the 7.
After identifying the position, we need to determine if this number remains 7 or if we need to round it up to 8. If the number to the right of the tenth's place is 4 or lower, then our number will remain 7. If it is 5 or greater, then we will round the 7 up to 8.
In this case, the number is indeed 5, so our tenth's place becomes 8. All numbers to the left of the tenth's place will remain the same.
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To subtract decimals you place the first decimal over the top of the other aligned by the decimal point. If there are no numbers after a tens, hundredths, or thousandths place or further to the right of the decimal just add a zero in the required areas.
For example 
becomes 
Then go through each place and subtract the top number by the bottom number. Subtract the numbers in each place like you would any number.
The example we are working with will look like this 
The answer after subtraction is 
To subtract decimals you place the first decimal over the top of the other aligned by the decimal point. If there are no numbers after a tens, hundredths, or thousandths place or further to the right of the decimal just add a zero in the required areas.
For example
Then go through each place and subtract the top number by the bottom number. Subtract the numbers in each place like you would any number.
The example we are working with will look like this
The answer after subtraction is
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Subtract: 
Subtract:
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Rewrite the decimal as a fraction and subtract:
Reduce this:
Rewrite the decimal as a fraction and subtract:
Reduce this:
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Evaluate: 
Evaluate:
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Add the first two numbers, making sure you align the decimal points in the addends and the sum:
Now subtract the third number, making sure you again align the decimal points:
Add the first two numbers, making sure you align the decimal points in the addends and the sum:
Now subtract the third number, making sure you again align the decimal points:
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Combine:
Combine:
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First, combine the positive decimals, which gives you 
.
Then, you can subtract that from 
, but remember that your answer is negative since it's a 
.
Your answer is 
.
First, combine the positive decimals, which gives you
Then, you can subtract that from
Your answer is
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Write the value of this expression as a decimal:
Write the value of this expression as a decimal:
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Simplify the sum by taking the least common denominator, which is 12:
Divide 13 by 12:
Simplify the sum by taking the least common denominator, which is 12:
Divide 13 by 12:
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Which of the following is the sum of nine tenths and nineteen thousandths?
Which of the following is the sum of nine tenths and nineteen thousandths?
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Nine tenths is equal to 0.9; nineteen thousandths is equal to 0.019. Add them, rewriting 0.9 as 0.900:
Nine tenths is equal to 0.9; nineteen thousandths is equal to 0.019. Add them, rewriting 0.9 as 0.900:
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Simplify the following:
Simplify the following:
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To add decimals, first add zeros to the necessary terms so they all have the same number of places to the right of the decimal point.
Now, temporarily drop the decimal and add the numbers as if they were whole numbers.
Finally, add the decimal place back in, in the same place you removed it from. In this case, we originally modified our numbers so they all had 3 numbers to the right of the decimal, so we will add the decimal back to the exact same place. Thus, our answer is:
To add decimals, first add zeros to the necessary terms so they all have the same number of places to the right of the decimal point.
Now, temporarily drop the decimal and add the numbers as if they were whole numbers.
Finally, add the decimal place back in, in the same place you removed it from. In this case, we originally modified our numbers so they all had 3 numbers to the right of the decimal, so we will add the decimal back to the exact same place. Thus, our answer is:
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Add: 
Add:
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Rewrite the problem so that the tenths, hundredths, and thousandths digits align. Use zeros as placeholders and solve.
Rewrite the problem so that the tenths, hundredths, and thousandths digits align. Use zeros as placeholders and solve.
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