Math Help: How to Work Out a Fraction of a Number

Mark, a math enthusiast, loves writing tutorials for stumped students and those who need to brush up on their math skills.

Whether you're a student doing homework, a chef working on a recipe, a wedding planner trying to lay out a budget, or just an average person strolling through life, chances are you'll eventually need to figure out a fraction of a number. In this article, we'll define a few simple terms, learn how to find any fraction of any number, and explore some example problems for practice. Ready? Let's do it!

Important Terms

• Fraction: A fraction is a portion of a whole. Think of it in terms of pizza—if there are 10 slices total in a pizza pie, and you've had three pieces, that means you've eaten 3/10 (three tenths) of the pie. The fraction 3/10 represents the portion of the whole pizza you've eaten.
• Numerator: In a fraction, the numerator is the number on top of (or before) the line. In the example above, 3 is the numerator of the fraction 3/10.
• Denominator: In a fraction, the denominator is the number below (or after) the line. In the example above, 10 is the denominator of the fraction 3/10.

How to Find a Fraction of a Number

To work out a fraction of a number, all you need to do is divide that number by the denominator of the fraction, then multiply your result by the numerator of the fraction.

For instance, if we wanted to find out what 3/8 of 24 is, we would divide 24 by 8 (the denominator of the fraction).

24 ÷ 8 = 3

We would now multiply this result by 1 (the numerator of the fraction).

3 x 3 = 9

So, 3/8 of 24 is 9.

Video Demonstration

Example Problems

Remember—to work out a fraction of a number, all you need to do is divide that number by the denominator of the fraction and then multiply the result by the numerator of the fraction. Let's do some example problems for practice.

Example 1: Work out 3/8 of 48

First, divide 48 by the denominator:

48 ÷ 8 = 6 (this is 1/8 of 48)

Now, multiply this result by the numerator:

6 × 3 = 18 (this is 3/8 of 48)

So, 3/8 of 48 is 18.

Example 2: Work out 2/9 of 36

First, divide 36 by the denominator:

36 ÷ 9 = 4 (this is 1/9 of 36)

Now, multiply this result by the numerator:

4 × 2 = 8 (this is 2/9 of 36)

So, 2/9 of 36 is 8.

Example 3: Work out 4/5 of 60

First, divide 60 by the denominator:

60 ÷ 5 = 12 (this is 1/5 of 60)

Now, multiply this result by the numerator:

12 × 4 = 48 (this is 4/5 of 60)

So, 4/5 of 60 is 48.

Example 4: Work out 5/11 of 77

First, divide 77 by the denominator:

77 ÷ 11 = 7 (this is 1/11 of 77)

Now, multiply this result by the numerator:

7 × 5 = 35 (this gives 5/11 of 77)

So, 5/11 of 77 is 35.

Example 5: Word Problem

A fuel tank holds 14 gallons of fuel when full. If the tank has 3/7 of fuel left in the tank, work out how many gallons of fuel are left.

Here, you need to calculate 3/7 of 14 gallons

First, divide 14 by the denominator:

14 ÷ 7 = 2 (this is 1/7 of 14)

Now, multiply this result by the numerator:

2 × 3 = 6 (this is 3/7 of 14)

So, there are 6 gallons of fuel left in the tank.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

Questions & Answers

Question: 12 is 3/4 of what number?

Answer: You need to divide by the top and multiply by the bottom.

12 divided by 3 is 4, and 4 times 4 is 16.

Question: What part of 5 3/5 is 7/10?

Answer: You will need to divide 7/10 by 5 3/5.

Convert 5 3/5 into an improper fraction which is 28/5

Now work out 7/10 divide by 28/5 which is the same as 7/10 times.

The answer is 1/8.

Question: What is 1/7 of 3.50?

Answer: Just divide 3.50 by 7 as 1/7 means divide by 7. This will give an anwer of 0.5.

Question: What is 1/8 of an hour?

Answer: 60 divided by 8 is 7.5, so 7.5 minutes.

Question: If 2/7 of an amount is 40, what is the whole amount?

Answer: You need to use the rule divide by the top and times by the bottom, as you are after the original amount.

40 divided by 2 is 20, and 20 times 7 is 140.

Question: What is 1/9 of 96?

Answer: To work out one ninth of a number divide the number by 9.

So 96 divided by 9 gives 10.7 (rounded to 1 decimal place).

Question: What is 4/5 of 30?

Answer: First work out 1/5 of the number by dividing by 5, so 30 divided by 5 is 6.

Now work out 4/5 by mutiplying the answer by 4, so 6 multiplied by 4 gives 24.

Question: What is 7/10 - 2/3?

Answer: First make the denominators the same by putting 30 on the bottom of both fractions.

S0 7/10 = 21/30, and 2/3 = 20/30

Now 21/30 - 20/30 is 1/30.

Question: What is 3/5 of 60 and how do you calculate it?

Answer: Divide 60 by 5 to give 12, then multiply 12 by 3 to give 36.

Follow the rule divide by the bottom and times by the top.

Question: 1/6 of what number is 11?

Answer: To find one sixth of something you divide by 6.

But since you have the answer already to the question, then multiply the 11 by 6 instead to give 66.

Question: 7/8 of a number is 56, what is the number?

Answer: 56 divided by 7 is 8, and 8 times 8 is 64.

Question: What is 1\5 x 4\5?

Answer: Just multiply the numerators and denominators together of both fractions to give 4/25.

Question: What is 2/8 of 32?

Answer: Work out one eighth by dividing by 8 to give 4. Now multiply 4 by the 2 to give 8.

Alternatively, cancel 2/8 down to 1/4 and work out 1/4 of 32 to give 8 by dividing by 4.

Question: What is 2/3 of 6?

Answer: Follow the rule divide by the bottom and times by the top.

6 divided by 3 is 2, and 2 times 2 is 4.

Question: What is 1/7 of 77?

Answer: To work out one-seventh of a number divide the number by 7.

So 77 divided by 7 is 11.

Question: What is 2/5ths of 60?

Answer: Divide 60 by 5 to give 12, and 12 times by 2 is 24.

Question: What is 3/7 of 28 ?

Answer: 28 divided by 7 is 4, and 4 times 3 is 12.

Question: What’s 5/6 of 18?

Answer: 18 divided by 6 is 3, and 3 times 5 is 15.

Question: What is 5/6 of 240?

Answer: Follow the rule divide by the bottom and times by the top.

240 divided by 6 is 40, and 40 times 5 is 200.

Question: What is3/8+11/12=?

Answer: This is the same as working out 9/24 + 22/24 which is 31/24.

Question: What is 5/8 of 40 ?

Answer: 40 divided by 8 is 5, and 5 multiplied by 5 is 25.

Question: What is 5/6 of 66?

Answer: Follow the rule divide by the bottom and times by the top.

66 divided by 6 is 11, and 11 multiplied by 5 is 55.

Question: What is 35% of 420?

Answer: 1% of 4.20, and 4.20 times 35 is 147.

Question: What is 6/8 of 40?

Answer: 40 divided by 8 is 5, and 5 multiplied by 6 is 30.

Question: What is 1/8 of £499?

Answer: Just divide 499 by 8 to give 62.375.

Question: What is 1/5th of 5/10 ?

Answer: Its easier just to multiply the fractions together as of means times (1/5 times 5/10 is 5/50).

5/50 can be simplified to 1/10.

Question: What is 5/11 of 176?

Answer: 176 divided by 11 is 16, and 16 times 5 is 80.

Question: What is 4/7 more than 63?

Answer: You need to use the rule "divide by the bottom and times by the top". 63 divided by 7 = 9, and 9 multiplied by 4 is 36. Finally add the 36 on to the 63 to give 99.

Question: What is 4/7 of 14?

Answer: Follow the rule, "divide by the bottom and times by the top".

So 14 divided by 7 = 2, and 2 multiplied by 4 = 8.

Question: What is 1/8 of 6?

Answer: To find 1/8 divide the number by 8.

6 divided by 8 gives 0.75.

Question: What is 5/7 of 100?

Answer: Divide 100 by 7 to get 14.28. 14.28 multiplied by 5 is 71.4, rounded to 1 decimal place.

Question: How do you figure out what is 5/8 of 4/5?

Answer: You can still use the rule divide by the bottom and times by the top even if your amount is a fraction.

Divide 4/5 by 8 to give 1/10, now multiply 1/10 by 5 to give 1/2.

Question: What is 1/8 of 14?

Answer: 1/8 of a number can be found by dividing the number by 8.

So 14 divided by 8 gives 1.75.

Question: What is 1/5 of 7?

Answer: 1/5 of a number can be found by dividing the number of 5.

Therefore, 7 divided by 5 gives 1.4

Question: 8% of 60 is 1/5 of what number?

Answer: First work out 8% of 60 which is 4.8.

So one fifth of something is 4.8.

Since 1/5 means divide by 5, multiply 4.8 by 5 to find the missing number.

The asnwer will be 24.

Question: What is 3/6 of 248?

Answer: Its probably easier to cancel 3/6 down to 1/2, so you need to work out one half of 248.

So 248 divided by 2 gives 124.

Question: What is 1/9 of 12?

Answer: To find 1/9 of a number divide the number by 9.

12 divided by 9 is 4/3 or 1.3 recurring.

Question: If 1/9 is 49 what is the number?

Answer: Just multiply 49 by 9 to give 441.

Question: What is 1/5 of 8?

Answer: To work out 1/5 divide the number by 5.

8 divided by 5 is 1.6.

Question: What is 9/13 of 182?

Answer: Divide 182 by 13 to give 14, then multiply 14 by 9 to give 126.

Question: What is 1/7 0f 15000?

Answer: To work out 1/7 of a number divide the number by 7.

So 15000 divided by 7 gives 2142.86 rounded to decimal places.

Question: How do you calculate 1/7 x 4?

Answer: 4 can be written as a fraction as 4/1.

Now, multiply the two fractions together 1/7 times 4/1 = 4/7.

Question: Orla spent one-quarter of her money on a t-shirt, and 3 eighths on a jumper. What fraction of her money had she left?

Answer: She spent 5/8 on clothes if you add the two fractions together, so 3/8 are left over.

Question: What is 4/11 of 66?

Answer: Use the method divide by the bottom and times by the top.

66 divided by 11 is 6, and 6 times 4 is 24.

Question: What is 4/5 of 12?

Answer: Follow the rule divide by the bottom and multiply by the top.

12 divided by 5 is 2.4, and 2.4 times 4 is 9.6.

Question: Can you work out 3/12 of 48?

Answer: Follow the rule divide by the denominator and multiply by the numerator.

48 divided by 12 gives 4, and 4 multiplied 3 gives 12.

Question: 2/3 of a number is 24. What is 5/9 of the number?

Answer: First divide 24 by to to give 12, and multiply 12 by 3 to give 36.

Now find 5/9 of 36, by dividing 36 by 9 to give 4, and multiplying 4 by 5 to give 20.

Question: Is 3/14 less than 6/7?

Answer: Multiply the numerator and denominator of 6/7 to give 12/14, so 3/14 is less than 6/7.

Question: What is 3/7 of 84?

Answer: 84 divided by 7 is 12, and 12 multiplied by 3 is 36.

Question: 3/4 of what number is 96?

Answer: You will need to apply the rule divide by top and multiply by the bottom.

96 divided by 3 is 32, and 32 times 4 is 128.

© 2011 Mark

Comments

Offenderman on April 22, 2018:

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bum face on February 21, 2013:

Thanks this helped!!! Xxxxxx