Math · Stage 4
Multiply a Fraction by a Whole · Add & Subtract Related Denominators
To multiply a proper fraction by a whole number, multiply the TOP and keep the bottom. To add or subtract fractions whose bottoms are related, rename to the bigger bottom — then work the tops.
✦ Math📘 Stage 4 · S4⏱ ~12 min🧒 Ages 8–9★ Free to start
I can multiply a proper fraction by a whole number; add and subtract fractions with related denominators.
📖
Kavi Shares the Pizza Slices 🍕
Kavi grabs three slices, each one-fifth of a pizza 🍕. "Three groups of 1/5," hoots Kavi, "that's 1/5 × 3 = 3/5 — I just multiply the top!" Then a friend brings 1/4 more cake. "To add it to my 1/2, I'll cut the half into quarters first — 1/2 = 2/4 — now the bottoms match and I can add: 2/4 + 1/4 = 3/4!"
🎓
What your child will learn
1Start with one-fifthHere is a whole cut into 5 equal parts with 1 shaded — that is 1/5. The top number counts how many slices you have; the bottom says how big each slice is. Keep your eye on the top — it is about to grow.
2Multiply a fraction × a whole = multiply the TOPTake 3 groups of 1/5. That is 1/5 + 1/5 + 1/5, which we write as 1/5 × 3. Shade three fifths. The slices are still fifths, so the bottom stays 5; only the top grows: 1 × 3 = 3.
3Add related denominators: rename, then add the topsTo add 1/2 + 1/4 the bottoms are different — but 4 is a multiple of 2, so they are related. Rename the half into quarters: 1/2 = 2/4. Now both are quarters. Shade 3 of the 4 parts to show 2/4 + 1/4.
4Two jobs, two rulesThis objective has two moves. Each has one clear rule. Tap each card.
🔍
A peek inside
Work out 2/5 × 3.
multiply the top by 3, keep the bottom: 2×3 = 6 over 5
Try this at home: Multiply the top, keep the bottom: 1/4 × 3 = __
Ready to play and learn?
Start the free interactive lesson, or print the handout for screen-free play.
Part of Math · Stage 4 · S4 on KAVI Academy — a secular, whole-child learning platform for ages 5–12.