Basic Math

Fractions | Seventh Grade

Fractions - Seventh Grade

Complete Notes & Formulas

1. Understanding Fractions

What is a Fraction?

numerator/denominator

Numerator: Top number (parts you have)

Denominator: Bottom number (total parts)

Types of Fractions

TypeDefinitionExample
Proper FractionNumerator < Denominator3/4, 2/5, 7/8
Improper FractionNumerator ≥ Denominator7/4, 9/5, 11/3
Mixed NumberWhole number + Proper fraction2 1/3, 5 2/7

2. Equivalent Fractions

Definition

Equivalent fractions have DIFFERENT numerators

and denominators but represent the SAME VALUE

Example: 1/2 = 2/4 = 3/6 = 4/8

Method 1: Multiply by Same Number

a/b × n/n = a×n/b×n

Multiply both numerator and denominator by the SAME number

Example: Find equivalent fractions of 2/3

Multiply by 2: 2/3 × 2/2 = 4/6

Multiply by 3: 2/3 × 3/3 = 6/9

Multiply by 4: 2/3 × 4/4 = 8/12

Answer: 2/3 = 4/6 = 6/9 = 8/12

Method 2: Divide by Same Number

Divide both numerator and denominator by a COMMON FACTOR

This simplifies the fraction

3. Simplifying Fractions to Lowest Terms

What is Lowest Terms?

A fraction is in LOWEST TERMS when the

numerator and denominator have NO common factors

other than 1 (they are relatively prime)

Formula

a/b ÷ GCF/GCF = a÷GCF/b÷GCF

Divide both by the Greatest Common Factor (GCF)

Steps to Simplify

Step 1: Find the GCF of numerator and denominator

Step 2: Divide both numerator and denominator by GCF

Step 3: The result is the simplified fraction

Example: Simplify 24/36

Step 1: Find GCF(24, 36)

Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24

Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18, 36

GCF = 12

Step 2: Divide both by 12

24 ÷ 12 = 2

36 ÷ 12 = 3

Answer: 24/36 = 2/3

4. Least Common Denominator (LCD)

What is LCD?

LCD is the SMALLEST common denominator

for a set of fractions

• It's the LCM (Least Common Multiple) of denominators

• Needed for adding and subtracting fractions

How to Find LCD

Step 1: List multiples of each denominator

Step 2: Find the smallest common multiple

Step 3: That's your LCD!

Example: Find LCD of 1/4 and 1/6

Multiples of 4: 4, 8, 12, 16, 20, 24...

Multiples of 6: 6, 12, 18, 24, 30...

Smallest common multiple: 12

Convert to LCD:

1/4 = 3/12 (multiply by 3/3)

1/6 = 2/12 (multiply by 2/2)

Answer: LCD = 12

5. Comparing and Ordering Fractions

Method 1: Same Denominator

If denominators are SAME:

Compare the NUMERATORS

Larger numerator = Larger fraction

Example: 5/8 > 3/8 (because 5 > 3)

Method 2: Same Numerator

If numerators are SAME:

Compare the DENOMINATORS

Smaller denominator = Larger fraction

Example: 2/3 > 2/5 (because 3 < 5)

Method 3: Different Numerators and Denominators

Step 1: Find the LCD of both fractions

Step 2: Convert both fractions to LCD

Step 3: Compare numerators

Example: Compare 2/3 and 3/4

Step 1: LCD of 3 and 4 is 12

Step 2: Convert to LCD

2/3 = 8/12 (multiply by 4/4)

3/4 = 9/12 (multiply by 3/3)

Step 3: Compare: 8/12 < 9/12

Answer: 2/3 < 3/4

6. Converting Between Mixed Numbers and Improper Fractions

Mixed Number to Improper Fraction

ab/c = (a×c)+b/c

Step 1: Multiply whole number × denominator

Step 2: Add the numerator

Step 3: Write result over original denominator

Example: Convert 3 2/5 to improper fraction

Step 1: 3 × 5 = 15

Step 2: 15 + 2 = 17

Step 3: 17/5

Answer: 3 2/5 = 17/5

Improper Fraction to Mixed Number

Step 1: Divide numerator by denominator

Step 2: Quotient = whole number

Step 3: Remainder = new numerator

Step 4: Denominator stays the same

Example: Convert 23/4 to mixed number

Step 1: 23 ÷ 4 = 5 remainder 3

Step 2: Whole number = 5

Step 3: Remainder = 3 (new numerator)

Step 4: Denominator = 4

Answer: 23/4 = 5 3/4

7. Rounding Mixed Numbers

Rounding Rule

Look at the FRACTION PART:

• If fraction ≥ 1/2 → ROUND UP

• If fraction < 1/2 → ROUND DOWN (stay same)

How to Check if Fraction ≥ 1/2

Compare: numerator ≥ (denominator ÷ 2)

If YES → Round up

If NO → Stay the same

Examples

Example 1: Round 7 3/4

Is 3/4 ≥ 1/2?

Half of 4 is 2

3 ≥ 2? Yes!

Round UP: 7 → 8

Answer: 8

Example 2: Round 12 1/3

Is 1/3 ≥ 1/2?

Half of 3 is 1.5

1 < 1.5

Round DOWN (stay same): 12

Answer: 12

Example 3: Round 9 5/8

Is 5/8 ≥ 1/2?

Half of 8 is 4

5 ≥ 4? Yes!

Round UP: 9 → 10

Answer: 10

Quick Reference: Fraction Formulas

ConceptFormula/Rule
Equivalent Fractionsa/b = (a×n)/(b×n) or (a÷n)/(b÷n)
Simplify to Lowest TermsDivide by GCF
LCDLCM of denominators
Mixed to Impropera b/c = (a×c+b)/c
Improper to MixedDivide: quotient remainder/denominator
Round Mixed NumbersIf fraction ≥ 1/2, round up

💡 Important Tips to Remember

Equivalent fractions: Multiply/divide numerator AND denominator by same number

Lowest terms: Divide by GCF until no common factors remain

LCD is needed for adding, subtracting, and comparing fractions

Same denominator: Compare numerators (larger numerator = larger fraction)

Same numerator: Compare denominators (smaller denominator = larger fraction)

Different numerators and denominators: Convert to LCD first

Mixed to improper: Multiply, add, keep denominator

Improper to mixed: Divide, quotient is whole, remainder is numerator

Rounding: Compare fraction to 1/2 (numerator vs half of denominator)

Always simplify your final answer to lowest terms

🧠 Memory Tricks & Strategies

Equivalent Fractions:

"Whatever you do to the top, do to the bottom too!"

Simplifying:

"Find the GCF and divide it right - makes the fraction small and tight!"

Comparing Fractions:

"Same bottom? Compare the top! Same top? Smaller bottom is on top!"

Mixed to Improper:

"Multiply, add, and place - denominator stays in its space!"

Improper to Mixed:

"Divide to decide the whole, remainder's the goal!"

Rounding Mixed Numbers:

"Half or more? Raise the score! Less than half? Just laugh!"

Master Fractions! 🍕 ✨

Remember: Fractions are parts of a whole - practice makes perfect!

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