Chapter 2: Toy Joy

A box of toys is a treasure chest of maths! Cars roll, marbles bounce, dolls smile , and every time we count, share, lose or find a toy, we are doing maths without even knowing.

What we'll learn

Add two numbers quickly in our head.
Subtract small numbers without writing long steps.
Use clever shortcuts like "make a ten".
Tell stories from a maths sentence and the other way around.
Check our answers by counting again.

The big idea

Adding is just "putting together". If you have 7 marbles and your friend gives you 5 more, you do not need a calculator. You can think: "7 plus 3 makes 10, then 2 more makes 12." Splitting a number to make a ten is a powerful trick.

Subtracting is "taking away" or "finding the gap". If you had 15 toy cars and gave away 6, you can think: "From 15 down to 10 is 5 steps, then 1 more step is 6 , so 9 are left."

Maths is a friend that lives inside stories. "Ravi had 12 chocolates. He ate 4. How many are left?" The story turns into 12 − 4 = 8. Once we see the story, the numbers stop hiding.

Sometimes we do not need an exact answer; we just need to be close. If a packet has "about 20" toffees and another has "about 30", we can say there are "about 50" in total. That is called estimating.

Let's explore

Marble jar. Put 8 marbles in one hand and 6 in the other. Without counting all of them, find the total by first moving 2 marbles to make a group of 10.

Toy shop pretend. Make price tags for 5 of your toys (Rs 4, Rs 7, Rs 10, Rs 12, Rs 15). Pick any two toys and add their prices. Do this 5 times.

Hop on the number line. Draw a line with marks 0 to 20 on paper. Start at 13 and hop back 5 steps. Where do you land?

Estimate first, count later. Grab a handful of dal grains. Guess how many. Then count. How close was your guess?

Worked examples

Example 1. A boy has 9 toy soldiers. His sister gives him 4 more. How many now?

9 + 1 = 10 (we took 1 from the 4).
3 are still left to add.
10 + 3 = 13.
He has 13 toy soldiers.

Example 2. Subtract: 14 − 6.

From 14, take away 4 to reach 10.
2 more still to take away.
10 − 2 = 8.

Example 3. A toy car costs 12 rupees. A toy ball costs 8 rupees. What is the total?

12 + 8 = 20.
The total is 20 rupees.

Quick check

Add: 7 + 8 = ?
Subtract: 13 − 5 = ?
Write a story for 6 + 9 = 15.
Estimate first, then add: 19 + 21.
There were 16 laddoos. Children ate 9. How many are left?

Recap

"Make a ten" makes adding easier.
Subtraction can be done by counting up or counting back.
Every maths sentence can be turned into a story, and every story into a sentence.