Solve the Fraction Subtraction: 1/4 minus 1/8 Step-by-Step

Q: Why can't I just subtract 1/4 - 1/8 directly?

You can only subtract fractions when they have the same denominator! Think of it like subtracting different units - you can't subtract 2 apples from 3 oranges without converting them first.

Q: Do I always need to simplify my answer?

Yes, always simplify! Check if the numerator and denominator have common factors. In this case, $ \frac{1}{8} $ is already in simplest form since 1 and 8 share no common factors.

Q: What's the fastest way to check my work?

Add your answer back to the second fraction: $ \frac{1}{8} + \frac{1}{8} = \frac{2}{8} = \frac{1}{4} $. If you get the first fraction, you're correct!

Fraction Subtraction with Different Denominators

Solve the following exercise:

$\frac{1}{4}-\frac{1}{8}=\text{?}$

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Solve

00:03 Multiply by 2 to find the common denominator

00:09 Make sure to multiply both numerator and denominator

00:16 Calculate the products

00:21 Subtract with the common denominator

00:28 Calculate the numerator

00:32 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

Solve the following exercise:

$\frac{1}{4}-\frac{1}{8}=\text{?}$

Step-by-step solution

To solve the problem $\frac{1}{4} - \frac{1}{8}$ , we need to subtract these two fractions:

Step 1: Determine the common denominator.
The denominators are 4 and 8. The least common multiple of 4 and 8 is 8.

Step 2: Convert each fraction to an equivalent fraction with the common denominator of 8.
- Convert $\frac{1}{4}$ to $\frac{1 \times 2}{4 \times 2} = \frac{2}{8}$
- The fraction $\frac{1}{8}$ already has the denominator 8.

Step 3: Subtract the numerators.
Subtract $\frac{1}{8}$ from $\frac{2}{8}$ :
$\frac{2}{8} - \frac{1}{8} = \frac{2 - 1}{8} = \frac{1}{8}$

The resulting fraction is already in its simplest form.

Therefore, the solution to the problem is $\frac{1}{8}$ .

Final Answer

$\frac{1}{8}$

Key Points to Remember

Essential concepts to master this topic

Common Denominator Rule: Find LCD before subtracting fractions with different denominators
Conversion Technique: Change $\frac{1}{4}$ to $\frac{2}{8}$ by multiplying by $\frac{2}{2}$
Verification Method: Check that $\frac{2}{8} - \frac{1}{8} = \frac{1}{8}$ by adding back: $\frac{1}{8} + \frac{1}{8} = \frac{2}{8} = \frac{1}{4}$ ✓

Common Mistakes

Avoid these frequent errors

Subtracting denominators along with numerators
Don't subtract 4 - 8 = -4 in the denominator like $\frac{1-1}{4-8} = \frac{0}{-4}$ ! This completely breaks fraction rules and gives meaningless results. Always keep the common denominator the same and only subtract the numerators.

Practice Quiz

Test your knowledge with interactive questions

Solve the following exercise:

$\frac{8}{5}-\frac{4}{5}=\text{?}$

FAQ

Everything you need to know about this question

Why can't I just subtract 1/4 - 1/8 directly?

You can only subtract fractions when they have the same denominator! Think of it like subtracting different units - you can't subtract 2 apples from 3 oranges without converting them first.

How do I find the least common denominator?

List the multiples of each denominator and find the smallest one they share. For 4 and 8: 4: 4, 8, 12... and 8: 8, 16, 24... The LCD is 8!

What if the LCD is a bigger number?

No problem! The process stays the same. Convert both fractions to the LCD, then subtract. A bigger LCD just means you're working with larger equivalent fractions.

Do I always need to simplify my answer?

Yes, always simplify! Check if the numerator and denominator have common factors. In this case, $\frac{1}{8}$ is already in simplest form since 1 and 8 share no common factors.

Can the answer be zero or negative?

Absolutely! If you subtract a larger fraction from a smaller one, you'll get a negative result. If you subtract equal fractions, you'll get zero. Both are valid answers.

What's the fastest way to check my work?

Add your answer back to the second fraction: $\frac{1}{8} + \frac{1}{8} = \frac{2}{8} = \frac{1}{4}$ . If you get the first fraction, you're correct!

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