Chapter 6: Decoration for Festival

It is festival time! Diyas to be lit, garlands to be hung, sweets to be shared. To get everything ready, we will need to add and to take away.

What we'll do

• Add two-digit numbers, with and without regrouping.
• Subtract two-digit numbers, with and without regrouping.
• Solve simple word problems from real life.

The big idea

When we put two groups together, we add. If amma made 24 ladoos and dadi made 15, how many in all? We add: 24 + 15 = 39 ladoos.

To add two-digit numbers, we add the ones first, then the tens. Sometimes the ones add up to more than 9. Then we make one new ten and carry it over. This is called regrouping. For example, 27 + 18: the ones 7 + 8 = 15, which is 1 ten and 5 ones. We write 5 in the ones place and carry 1 to the tens. Then 1 + 2 + 1 = 4 tens. So 27 + 18 = 45.

When we take some away from a group, we subtract. If we had 50 marigold flowers and used 23 for one garland, how many are left? 50 - 23 = 27.

In subtraction also, sometimes the ones on top are smaller than the ones below. Then we borrow one ten from the tens place and break it into 10 ones. This is regrouping in subtraction.

Let's play!

Diya counting. Take 36 small stones to be diyas. Add 18 more. How many diyas now? Try the sum on paper. Match!

Garland subtraction. Make a paper garland with 25 flowers. Tear off 9. How many are left? Did you need to borrow?

Sweet shop. You have 45 rupees. You buy a sweet for 18 rupees. How many rupees left? Use coins to act it out.

A small story

For Diwali, Rani's family made 38 sweets in the morning and 27 more in the evening. How many sweets in all? 38 + 27 = 65 sweets. They shared 19 with neighbours. How many did they keep? 65 - 19 = 46 sweets. The whole house smelled wonderful!

Quick check

1. 23 + 14 = ?
2. 36 + 28 = ?
3. 50 - 16 = ?
4. 72 - 35 = ?
5. There were 40 diyas. 22 were lit. How many are still not lit?

What did we learn?

• We add to put groups together and subtract to take away.
• If ones cross 9, we regroup into a new ten.
• Addition and subtraction help us in shopping, cooking and festivals.