Lesson 1.11: Fractions – Multiplying & Dividing | SEA Mathematics | My Carib Academy
SEA 2025-2028 Framework Aligned

✖️➗ Lesson 1.11: Fractions – Multiplying & Dividing

Master multiplying fractions by whole numbers and dividing fractions (whole by fraction, fraction by whole). This lesson covers SEA Mathematics Objectives 60-61, 64-67 from the Number Strand.

60 Minutes
Module 1: Number
Objectives 60-61, 64-67
2 Videos
Lesson Progress 0%

Previous Lesson

Did you complete Lesson 1.10? Review Adding & Subtracting Fractions →

Learning Objectives

By the end of this lesson, you will be able to:

  • Multiply fractions by whole numbers (Objectives 60-61)
  • Divide whole numbers by fractions (Objectives 64-65)
  • Divide fractions by whole numbers (Objectives 66-67)
  • Simplify answers to lowest terms
  • Solve word problems involving fraction multiplication and division

SEA Tip

Fraction multiplication and division appear in Section II and III of the SEA Math paper. These are worth 2-4 marks each! (SEA Framework Page 21-22)

Watch: Multiplying Fractions by Whole Numbers

Start by watching this video to learn how to multiply fractions by whole numbers. Take notes as you watch! 📝

Multiplying Fractions by Whole Numbers – Mathematics Video Lesson

Quick Check

Did you understand the video? Review the notes below before continuing! ✅

Multiplying Fractions by Whole Numbers

Multiplying fractions by whole numbers is easier than you think! Just follow these simple steps.

Step-by-Step Method

  1. Convert the whole number to a fraction (put it over 1)
  2. Multiply the numerators (top numbers)
  3. Multiply the denominators (bottom numbers)
  4. Simplify to lowest terms or convert to mixed number

📊 Example 1: Simple Multiplication

3 × 1/4 = ?

Solution:

  1. Convert: 3 = 3/1
  2. Multiply numerators: 3 × 1 = 3
  3. Multiply denominators: 1 × 4 = 4
  4. Answer: 3/4 (already simplified)

Answer: 3/4

📊 Example 2: Multiplication with Simplifying

4 × 2/3 = ?

Solution:

  1. Convert: 4 = 4/1
  2. Multiply numerators: 4 × 2 = 8
  3. Multiply denominators: 1 × 3 = 3
  4. Answer: 8/3 = 2⅔ (convert to mixed number)

Answer: 2⅔

📊 Example 3: Word Problem

Real-Life Application

Question: A recipe needs 2/5 cup of sugar. How much sugar is needed for 3 batches?

Solution:

  1. Set up: 3 × 2/5
  2. Convert: 3 = 3/1
  3. Multiply: (3 × 2)/(1 × 5) = 6/5
  4. Convert: 6/5 = 1⅕ cups

Answer: 1⅕ cups of sugar

Common Mistake

Don’t multiply the whole number by BOTH numerator and denominator! Only multiply by the numerator. The denominator stays the same (or multiply by 1).

Watch: Dividing Fractions

Now watch this video to learn how to divide whole numbers by fractions and fractions by whole numbers. Remember: Keep, Change, Flip! 🎯

Dividing Fractions – Mathematics Video Lesson

Dividing Fractions

Dividing fractions uses the Keep, Change, Flip method. This works for both whole ÷ fraction and fraction ÷ whole!

Keep, Change, Flip Method

  1. KEEP the first number (don’t change it)
  2. CHANGE ÷ to × (division to multiplication)
  3. FLIP the second number (find its reciprocal)
  4. Multiply and simplify

📋 Type 1: Whole Number ÷ Fraction

6 ÷ 1/3 = ?

Solution:

  1. KEEP: 6 stays as 6/1
  2. CHANGE: ÷ becomes ×
  3. FLIP: 1/3 becomes 3/1
  4. Multiply: 6/1 × 3/1 = 18/1 = 18

Answer: 18

📋 Type 2: Fraction ÷ Whole Number

3/4 ÷ 2 = ?

Solution:

  1. KEEP: 3/4 stays as 3/4
  2. CHANGE: ÷ becomes ×
  3. FLIP: 2 becomes 1/2
  4. Multiply: 3/4 × 1/2 = 3/8

Answer: 3/8

📊 Example 4: Word Problem

Real-Life Application

Question: Maria has 4 meters of ribbon. She needs 1/2 meter for each bow. How many bows can she make?

Solution:

  1. Set up: 4 ÷ 1/2
  2. Keep, Change, Flip: 4/1 × 2/1
  3. Multiply: 8/1 = 8

Answer: 8 bows

Memory Trick

KCF = Keep, Change, Flip – Just like a recipe! Keep the first, Change the sign, Flip the second!

Quick Quiz

Test your understanding! Select an answer for each question. ✖️➗

6 Questions
12 Minutes
70% to Pass

1. What is 3 × 2/5?

2. What is 4 × 3/8?

3. What is 6 ÷ 1/2?

4. What is 2/3 ÷ 4?

5. What does KCF stand for in fraction division?

6. A recipe needs 1/4 cup of oil. How much for 5 batches?

0/6

Lesson Complete!

Great job finishing Lesson 1.11! You’re mastering fraction operations for the SEA exam! 🎉

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