Chapter 9: Equal Groups

If 5 friends each get 4 toffees, how many toffees in total? You could add 4 + 4 + 4 + 4 + 4 , or you can multiply. Faster, smarter, and fun!

What we'll learn

Multiplication as repeated addition.
Multiplication tables of 2 to 10.
Multiply a 2-digit number by a 1-digit number.
Use arrays to picture multiplication.

The big idea

When we have equal groups, we don't need to add over and over. We multiply.

5 groups of 4 = 5 × 4 = 20. The 'times' sign × means "groups of".

An array is a neat rectangle of dots. 3 rows × 4 columns = 12 dots. Arrays make multiplication visible.

The multiplication table is a list of these answers. 7 × 8 = 56 is just 7 groups of 8. Knowing tables helps us answer fast.

There's a fairness rule: 3 × 4 is the same as 4 × 3. Both give 12. So you can flip the order to make the sum easier. 9 × 2 is easier as 2 × 9.

To multiply a bigger number like 23 × 4, split 23 into 20 + 3. Then 20 × 4 = 80 and 3 × 4 = 12. Add: 80 + 12 = 92.

Explore with examples

1. There are 6 plates with 7 chapatis on each. Total chapatis?

6 × 7 = 42 chapatis.

2. Multiply 24 × 5.

Split: (20 × 5) + (4 × 5) = 100 + 20 = 120.

3. Find 8 × 9.

From tables: 8 × 9 = 72. (Or: 8 × 10 = 80, then 80 − 8 = 72.)

4. Show 4 × 5 as an array.

Draw 4 rows of 5 dots each:

• • • • •
• • • • •
• • • • •
• • • • •

Total = 20 dots.

Hands-on activities

Egg Tray Maths

Look at an egg tray with 6 rows and 5 holes per row. Count without counting one by one. Use multiplication: 6 × 5 = 30.

Skip Counting Game

Stand in a circle. Take turns saying multiples of 3: 3, 6, 9, 12... Sit out if you get it wrong! Last one standing wins.

Bead Arrays

Use a thread and beads. Make 4 lines, each with 7 beads. Now count total beads. Try 5 lines of 6. Notice 4 × 7 and 5 × 6 are not the same, but 4 × 7 = 7 × 4.

Try it yourself

8 × 6 = ?
12 × 4 = ?
25 × 3 = ?
A box has 9 rows of 9 chocolates. Total chocolates?
Auto fare per km is ₹15. Cost for 6 km?
Write the table of 7 from 7 × 1 to 7 × 10.
100 × 23 = ? (Hint: just add two zeros!)

Recap

Multiplication is repeated addition of equal groups.
a × b = b × a (order doesn't matter).
Use arrays to picture multiplication.
Break big numbers into tens and ones to multiply mentally.