Percent means per hundred, from the Latin per centum. So is literally , a fraction whose denominator is . The sign is just a stand-in for that .
Problem
Your phone storage is full. Write as a fraction in lowest terms.
Show a hint
- The word percent means "per hundred," so put the number over 100. That gives you , and now it is just a fraction waiting to be simplified.
- Both 80 and 100 are divisible by 20. Divide the top by 20 and the bottom by 20 to land on the smallest equivalent fraction.
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means 80 per hundred, so . The greatest common factor of 80 and 100 is 20, so divide the top and the bottom by 20. So the answer is . Reducing does not shrink the amount, it just names the same slice of storage with smaller numbers.
Problem
A bakery sold as many sourdough loaves as last Saturday. Percents can exceed . Write as a fraction in lowest terms.
Show a hint
- A percent means that many hundredths, so is the same as . Going above is allowed, it simply gives a fraction larger than .
- Now reduce . Both the top and bottom share a factor of , so divide each by .
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A percent is a number of hundredths, so . The greatest common factor of and is , so divide the top and the bottom by . So in lowest terms is . Going past is fine, it just means more than one whole, and is , the two and a half times the bakery sold.
Problem
A glacier retreated by over a decade. A percent can be negative. Write as a fraction in lowest terms.
Show a hint
- Start from the meaning. means out of , so write it as . The negative sign just rides along on top.
- Now reduce . Both and share a factor of , so divide each by and keep the minus sign.
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means out of , so . Both and are divisible by , and dividing gives . Since and share no factor bigger than , that is lowest terms, so . The minus sign rides along on the numerator and changes nothing about how you reduce.
Problem
A coupon takes off. Rewrite as a decimal.
Show a hint
- A percent is a count per hundred, so . You are not taking the percent of any price yet, just rewriting the number itself.
- Dividing by slides the decimal point two places to the left. Picture as and hop that point left twice, filling the empty spot with a zero.
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, and dividing by moves the decimal point two places to the left. Start at , hop the point left once to get , then left again to land at . So .
Problem
A bridge sensor drifts by . Write as a decimal.
Show a hint
- A percent means "divided by one hundred", so dividing by slides the decimal point two places to the left. Start from and move the point.
- Moving the point in two places left runs out of digits, so fill the empty spots with zeros. You get .
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A percent is a count out of one hundred, so means . Dividing by slides the decimal point two places to the left. Starting at , one slide gives and a second slide gives , with zeros filling the empty places. So .
Problem
Your fitness app shows daily goal progress as the decimal . Write as a percent. Give just the number.
Show a hint
- A percent is a count out of one hundred, so to name a decimal as a percent you multiply it by . Multiplying by slides the decimal point two places to the right.
- Slide the point in two places right. It moves past the and past the , landing after the , which leaves .
Show the full solution
A decimal becomes a percent when you multiply it by , and multiplying by just slides the decimal point two places to the right. Start with . Slide the point past the to get , then past the to get . So , which means . The answer is .
Problem
A race lap timer reads of the way through the final lap. Write as a percent. Give just the number.
Show a hint
- To go from a decimal to a percent, multiply by , which slides the decimal point two places to the right. Start by moving it from one place, then a second place.
- Sliding two places right gives . Drop the leading zeros and you are left with a number that still has a digit after the point.
Show the full solution
To make a decimal into a percent, multiply by , which slides the decimal point two places to the right. From , one slide gives and a second gives , so and the number you type is . There were three digits after the point, so only two of them clear it and the last one stays behind in the tenths place. That is why the percent is itself a decimal.
Problem
A garden bed is planted. A percent has a hidden denominator of . Write as a percent. Give just the number.
Show a hint
- You want the same fraction with a denominator of . Ask yourself what must be multiplied by to reach , and remember to multiply the top by that same number.
- Since , multiply top and bottom by . That gives , and the numerator over is the percent.
Show the full solution
Rewrite as an equal fraction whose denominator is . Since , multiply the top and bottom by the same . A fraction over is read directly as a percent, so . The percent is .
Problem
A bakery scales a recipe to of the original. Since , the percent lands above . Write as a percent. Answer with just the number.
Show a hint
- To get a denominator of , ask what turns into . Since , multiply both the top and the bottom by .
- Multiplying gives . The numerator over is the percent.
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Since , rewrite with a denominator of by multiplying the top and bottom by . A fraction over reads straight off as a percent, so the answer is . Because is bigger than one whole, the percent lands above , exactly as expected.
Problem
A recipe calls for cups of oats. Since eighths do not divide evenly, multiply by and simplify. Write as a percent. Give just the number.
Show a hint
- To turn a fraction into a percent, multiply it by . So you want , which is the same as .
- Now simplify by dividing top and bottom by to get , then divide by . It does not come out even, so expect a decimal ending in a half.
Show the full solution
A fraction becomes a percent when you multiply it by . Divide the top and bottom by to get , and . So the number is . It clears because is more than one whole, and it carries a because halving an odd number leaves a half.
Problem
Room A chose pizza at . Room B chose pizza at . Convert both to decimals and pick the larger share. Type for Room A or for Room B.
Show a hint
- You cannot compare a percent and a fraction while they look different. Turn both into decimals first. For the percent, slide the point two places left. For the fraction, divide the top by the bottom.
- Room A is . Room B is . Now both are decimals, so just compare with and name the option that is bigger.
Show the full solution
Put both shares in decimal form. Room A is , and dividing by slides the point two places left, so . Room B is , and , which you can check with . Since , Room A has the larger share, option . Values in different forms cannot be judged by eye, so convert them to one shared form first.
Problem
A sales tax is . Write as a fraction in lowest terms.
Show a hint
- Percent means per hundred, so start by writing as . A fraction in lowest terms cannot keep a decimal upstairs, so you need to clear that half.
- Multiply the top and bottom by to get rid of the decimal point. That turns into , and now both numbers are whole and ready to simplify.
Show the full solution
Percent means per hundred, so . Multiply the top and bottom by to clear the decimal. Both and share the factor , and dividing each by it gives . Twelve and a half percent being exactly one eighth makes sense, since of a hundred is .
Practice these ideas
Practice
A survey found of students bike to school. Write as a fraction in lowest terms.
Show the solution
Percent means "per hundred," so is out of . Now reduce. The numerator and denominator both share a factor of , so divide each by . Since is prime and does not divide , the fraction is in lowest terms.
Practice
A pollster reports of people surveyed had never tasted dark chocolate. Write as a fraction in lowest terms.
Show the solution
The word percent means per hundred, so is out of . Now simplify. The greatest factor shared by and is , so divide both the numerator and the denominator by . Since and share no common factor larger than , this is fully reduced.
Practice
A loyalty card stamps your total at of last month. Write as a fraction in lowest terms.
Show the solution
Percent means per hundred, so . The greatest common factor of and is , so divide both parts by it. That gives . Since and share no factor bigger than , this is lowest terms, and it is more than one whole because .
Practice
A deep freezer drifted from its set point. Write as a fraction in lowest terms.
Show the solution
Percent means per hundred, so the number sits over and keeps its sign. That gives . The top and bottom share a common factor of , so divide both by . The numerator becomes and the denominator becomes . Since and have no common factor left, the fraction is in lowest terms. So equals .
Practice
A weather app says the chance of rain is . Write as a decimal.
Show the solution
A percent is just a number of hundredths, so means . Dividing by slides the decimal point two places to the left, turning into . So the decimal form is .
Practice
Write as a decimal.
Show the solution
To write a percent as a decimal you divide by , which slides the point two places to the left. Begin with , really , and move the point two places left to land between the and the first . So . The result is more than because is more than a whole.
Practice
A lab label reads saline. Write as a decimal.
Show the solution
A percent is just a number over 100, so means . Dividing by 100 slides the decimal point two places to the left. Starting from , one place left gives , and a second place gives , with placeholder zeros filling the gaps. So as a decimal is .
Practice
A probe is filled to of its tank. Write as a percent. Give just the number.
Show the solution
To turn a decimal into a percent, multiply by , which slides the point two places to the right. So , and the number to post is . It also reads straight off, since is already per hundred.
Practice
A grain of gold dust registers of a carat. Write as a percent. Give just the number.
Show the solution
To go from a decimal to a percent, multiply by , which slides the decimal point two places to the right. Sliding the point from two places to the right lands between the and the , so the value is . The number alone is .
Practice
A trail map marks of its loops as beginner-friendly. Write as a percent. Give just the number.
Show the solution
Multiplying by gives , so multiply the top by as well to keep the same value. A fraction over reads straight off as a percent, so the number is . Rescaling like this works whenever the denominator divides evenly.
Practice
A juice bottle is real fruit. Write as a percent. Give just the number.
Show the solution
To turn a fraction into a percent, multiply it by . So of the bottle is fruit, and the number is .
Practice
Write as a percent. Give just the number.
Show the solution
To write a fraction as a percent, multiply it by . That gives , and , so and the number is . That checks out, since is a bit more than and is a bit more than .
Practice
A pool is full. Write as a fraction in lowest terms.
Show the solution
Percent means per hundred, so . Multiply the top and bottom by to clear the decimal, which gives . Now reduce. Both numbers are divisible by , and while , so the fraction becomes . Since is prime and does not divide , this is lowest terms.
Practice
Option 1 is and option 2 is . Which value is larger? Type or .
Show the solution
Put both into percent form so they can be compared head to head. For the fraction, scale to a denominator of by multiplying top and bottom by , which gives . Now line them up, against . Since , option 1 is the larger value.
QuanticaPrealgebraOpen in the course