What Does It Mean to Multiply a Fraction by a Whole Number?
When you multiply a fraction by a whole number, you're essentially adding
that fraction to itself multiple times!
For example, 3 × ½ means ½ + ½ + ½. This equals 3/2 or 1½. It's like having three half-pizzas - together
they make one and a half whole pizzas!
How to Multiply Fractions by Whole Numbers
1️⃣ Write the whole number as a fraction (put it over 1, like 3 = 3/1)
2️⃣ Multiply the numerators (top numbers) together
3️⃣ Multiply the denominators (bottom numbers) together
4️⃣ Simplify your answer if needed
Let's Practice Together!
Example 1: Pizza Party!
You have 4 friends coming over, and each will eat 3/8 of a pizza. How much pizza do you need total?
Let's solve: 4 × 3/8 = ?
- Write 4 as a fraction: 4/1
- Multiply numerators: 4 × 3 = 12
- Multiply denominators: 1 × 8 = 8
- So, 4 × 3/8 = 12/8
- Simplify: 12 ÷ 8 = 1 4/8 = 1½
You'll need 1½ pizzas for your friends!
Each slice represents 1/8 of a pizza. 4 friends × 3/8 = 12 slices total. That's one whole pizza (8 slices) plus 4 more slices (half a pizza).
Example 2: Chocolate Bar Fractions
Imagine a chocolate bar divided into 5 equal pieces. If you have 3 whole chocolate bars, how many fifths do you have?
3 × 1/5 = 3/5, but since each whole bar has 5 pieces, 3 bars = 15 pieces = 15/5 = 3 whole bars!
Parent Tips 🌟
- Use real objects: Cut apples, pizzas, or chocolate bars to show how multiplying fractions works in real life.
- Relate to addition: Show how 3 × ¼ is the same as ¼ + ¼ + ¼ to build understanding before teaching the shortcut method.
- Practice with recipes: Double or triple recipe measurements (like 3 × ½ cup) to make math practical and delicious!