Subtracting Fractions — How to Subtract Fractions Step by Step

Subtracting fractions is one of the core skills in Grades 4–6 arithmetic. The key rule is simple: fractions must share the same denominator before you can subtract them. This guide walks through every case — like denominators, unlike denominators, mixed numbers, and improper fractions — with worked examples at each step.

A fraction represents a part of a whole and consists of two parts:

• Numerator: The top number, which shows how many parts you have.
• Denominator: The bottom number, which shows how many equal parts the whole is divided into.

Example: In the fraction $\frac{3}{4}$, 3 is the numerator and 4 is the denominator.

To subtract fractions, their denominators must be the same. When denominators differ, find a common denominator:

• The least common denominator (LCD) is the smallest number that both denominators can divide into evenly.
• To find the LCD, list multiples of each denominator and find the smallest matching multiple.

Example: For $\frac{1}{3}$ and $\frac{1}{4}$, multiples of 3 are 3, 6, 9, 12; multiples of 4 are 4, 8, 12. The LCD is 12.

Follow these steps to subtract fractions:

1. Check denominators: If denominators are different, find the LCD.
2. Adjust fractions: Rewrite fractions with the LCD as their denominator by multiplying numerator and denominator by the appropriate number.
3. Subtract numerators: Keep the denominator the same and subtract the numerators.
4. Simplify: Reduce the resulting fraction if possible.

Example 1: Subtract fractions with the same denominator

Subtract $\frac{5}{8}$ - $\frac{3}{8}$:

Since denominators are the same, subtract numerators: $\frac{\mathrm{(5\; -\; 3)}}{8}$ = $\frac{2}{8}$

Simplify: $\frac{2}{8}$ = $\frac{1}{4}$

Example 2: Subtract fractions with different denominators

Subtract $\frac{3}{4}$ - $\frac{1}{6}$:

1. Find LCD of 4 and 6. Multiples of 4: 4, 8, 12; multiples of 6: 6, 12. LCD = 12.
2. Convert: $\frac{3}{4}$ = $\frac{9}{12}$, $\frac{1}{6}$ = $\frac{2}{12}$
3. Subtract: $\frac{9}{12}$ - $\frac{2}{12}$ = $\frac{7}{12}$ (already simplified)

Example 3: Subtract improper fractions

Subtract $\frac{7}{5}$ - $\frac{3}{5}$:

Denominators match — subtract numerators: $\frac{\mathrm{(7\; -\; 3)}}{5}$ = $\frac{4}{5}$

Simplify a fraction by dividing numerator and denominator by their greatest common divisor (GCD):

• Example: Simplify $\frac{6}{9}$.
• GCD of 6 and 9 is 3.
• Divide both by 3: $\frac{6}{9}$ = $\frac{2}{3}$.

• Find a common denominator first. Never subtract numerators when the denominators are different.
• Keep the denominator unchanged. Only the numerators are subtracted — the denominator stays the same throughout.
• Simplify the result. Always reduce the fraction to its lowest terms after subtracting.
• Convert mixed numbers first. Change mixed numbers to improper fractions before subtracting to avoid borrowing errors.

The resources on this page are designed to take a learner from first principles through to confident independent practice.

1. Work Through the Guide

Read each section in order. The guide builds progressively — understanding what a denominator is comes before finding the LCD, which comes before working through full subtraction problems. Skipping ahead is fine for review, but the sequence is deliberate for first-time learners.

2. Practise with the Examples

Cover the worked examples and attempt each problem yourself before reading the solution. Self-testing is significantly more effective than passive reading for building procedural fluency.

3. Download Printable Worksheets

Use the subtracting fractions worksheets to practise on paper. Each generator creates a fresh set of problems so you can return as many times as needed without repeating the same sums.

4. Try the Game Worksheets

For a more engaging format, the subtraction fraction game worksheets — including maze formats — require students to solve problems and follow the correct path, adding a self-checking mechanism that plain drills lack.

Fraction subtraction is not an isolated skill — it underpins large areas of mathematics from Grade 4 upwards.

Foundation for Algebra

Finding a common denominator is the same process as finding a common expression when adding or subtracting algebraic fractions in secondary mathematics. Students who are fluent at fraction arithmetic reach algebra with one less barrier.

Builds Number Sense

Repeatedly working with fractions — converting, simplifying, comparing — builds an intuitive sense of how numbers relate to each other. This number sense is difficult to develop through whole-number arithmetic alone and pays dividends across the entire curriculum.

Controlled Difficulty Levels

The printable worksheet generators on this site let you choose denominator ranges precisely. This means you can target the exact difficulty level your students need — starting with simple like-denominator problems and progressing to two-digit unlike denominators as confidence grows.

Unlimited Unique Practice

Every click of the worksheet generators produces a new, unique set of problems. You can generate different worksheets for classwork, homework, and assessment across the full school year without students ever encountering the same problems twice.