What is Adding to Make Fifteen?

S0-SA1-1340

Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

Adding to make fifteen means finding two or more numbers that, when put together, give you a total of 15. It's about understanding different combinations of numbers that sum up to fifteen.

Simple Example

Quick Example

Imagine you have 7 ladoos. How many more ladoos do you need to have a total of 15 ladoos for your family? You need to add 8 more ladoos (7 + 8 = 15).

Worked Example

Step-by-Step

Let's say your cricket team scored 9 runs in the first over. How many more runs do you need to reach a target of 15 runs for a good start?
1. We know the total target is 15 runs.
2. We know the team already scored 9 runs.
3. To find out how many more runs are needed, we can subtract the runs already scored from the target: 15 - 9.
4. Counting up from 9 to 15 (9, 10, 11, 12, 13, 14, 15) shows a difference of 6.
5. So, 9 + 6 = 15.
--- The team needs 6 more runs to reach 15.

Why It Matters

Understanding how numbers combine to make a specific total is fundamental to all math. This skill helps you quickly calculate costs, manage money, and even understand data in sports. It's used by shopkeepers, data analysts, and even scientists.

Common Mistakes

MISTAKE: Only thinking of 7 + 8 = 15 and not other combinations. | CORRECTION: Remember there are many ways to make 15, like 10 + 5, 12 + 3, or even 5 + 5 + 5.

MISTAKE: Confusing addition with subtraction or multiplication. Forgetting to 'add' numbers together. | CORRECTION: Always ensure you are combining numbers to find a larger total, not taking away or multiplying.

MISTAKE: Miscounting when adding, especially with fingers or mental math. For example, saying 7 + 9 = 15. | CORRECTION: Double-check your addition by counting carefully or using a different method, like counting backwards from 15.

Practice Questions

Try It Yourself

QUESTION: You have 6 rupees. How many more rupees do you need to buy a small chai that costs 15 rupees? | ANSWER: 9 rupees (6 + 9 = 15)

QUESTION: Find two different pairs of numbers that add up to 15. | ANSWER: Examples: 1 + 14, 2 + 13, 3 + 12, 4 + 11, 5 + 10, 6 + 9, 7 + 8 (any two pairs are correct)

QUESTION: Your elder brother gave you 5 stickers, and your sister gave you 7 stickers. How many more stickers do you need to have a total of 15 stickers? | ANSWER: 3 stickers (5 + 7 = 12, then 12 + 3 = 15)

MCQ

Quick Quiz

Which of these pairs of numbers adds up to 15?

6 and 7

8 and 7

9 and 5

10 and 4

The Correct Answer Is:

8 + 7 = 15, so option B is correct. The other options are 6 + 7 = 13, 9 + 5 = 14, and 10 + 4 = 14.

Real World Connection

In the Real World

When you're shopping at the local kirana store and buy items for 7 rupees and 8 rupees, you quickly know the total is 15 rupees. This helps you give the correct change or check if you have enough money. Even online payment apps like UPI rely on these simple calculations to show your total bill.

Key Vocabulary

Key Terms

ADDITION: combining numbers to find a total | SUM: the result of adding two or more numbers | TOTAL: the whole amount or number | COMBINATION: different ways numbers can be put together

What's Next

What to Learn Next

Once you're comfortable adding to make fifteen, you can explore adding to make other numbers like 20 or 100. This will strengthen your number sense and prepare you for more complex addition and subtraction problems!