What is Adding to Make Thirteen?

S0-SA1-1338

Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

Adding to make thirteen means finding different pairs of numbers that, when put together, give you the total sum of thirteen. It's like having thirteen items and figuring out how you can split them into two groups and still have thirteen in total.

Simple Example

Quick Example

Imagine you have 13 ladoos. If you eat 5 ladoos, how many are left? You can think of it as 5 + what number makes 13? The answer is 8, because 5 + 8 = 13. So, you have 8 ladoos left.

Worked Example

Step-by-Step

Let's say your cricket team needs 13 runs to win. You score 7 runs in one over. How many more runs do you need to reach 13?
--- Step 1: We know the total runs needed is 13.
--- Step 2: We know your team has already scored 7 runs.
--- Step 3: We need to find the missing number that adds to 7 to make 13. We can write this as: 7 + ? = 13.
--- Step 4: To find the missing number, we can subtract the known part from the total: 13 - 7.
--- Step 5: 13 - 7 = 6.
--- Step 6: So, you need 6 more runs. This means 7 + 6 = 13.
--- Answer: You need 6 more runs to win.

Why It Matters

Understanding how numbers combine to make a specific total is a fundamental skill in mathematics. It's crucial for budgeting your pocket money, calculating scores in games, or even helping shopkeepers give correct change. This skill is vital for careers in finance, retail, and data analysis.

Common Mistakes

MISTAKE: Confusing addition with subtraction when finding the missing number. For example, thinking 7 + ? = 13 means 7 - 13. | CORRECTION: Remember that 'adding to make thirteen' means you're looking for a number that, when added to the first number, results in thirteen. If you have the total and one part, subtract the part from the total.

MISTAKE: Not checking your answer. For example, if you think 7 + 5 = 13. | CORRECTION: Always double-check your answer by adding the two numbers you found. 7 + 5 = 12, not 13, so 5 is incorrect. 7 + 6 = 13, so 6 is correct.

MISTAKE: Only thinking of one way to make 13. For example, only knowing 10 + 3 = 13. | CORRECTION: Explore different combinations! Practice with various numbers like 1+12, 2+11, 3+10, 4+9, 5+8, 6+7. This builds number sense.

Practice Questions

Try It Yourself

QUESTION: Your mom bought 13 oranges. You ate 4 of them. How many are left? | ANSWER: 9

QUESTION: On a train journey, you saw 6 stations before lunch. If there are 13 stations in total on your route, how many more stations will you see after lunch? | ANSWER: 7

QUESTION: A small shop has 13 packets of biscuits. If they sell 8 packets in the morning and want to restock to have 13 packets again, how many more packets do they need to buy? | ANSWER: 8 (They need 5 packets to reach 13. After selling 8, they have 5 left. To get back to 13, they need 8 more: 5 + 8 = 13)

MCQ

Quick Quiz

Which pair of numbers adds up to 13?

5 and 7

8 and 4

6 and 7

9 and 5

The Correct Answer Is:

Option C, 6 and 7, add up to 13 (6 + 7 = 13). Options A, B, and D result in 12, 12, and 14 respectively, not 13.

Real World Connection

In the Real World

When you buy items at a local kirana store and the total bill is, say, ₹13, and you give the shopkeeper a ₹20 note, they quickly calculate how much change to give you (₹7). This quick mental math relies on knowing that 13 + 7 = 20, or in our case, knowing how to 'add to make' 20.

Key Vocabulary

Key Terms

ADDITION: The process of combining numbers to find their total sum | SUM: The result of adding two or more numbers together | COMBINATION: A set of numbers that together form a specific total | TOTAL: The complete amount or number of something

What's Next

What to Learn Next

Great job understanding how to add to make thirteen! Next, you can explore 'Adding to Make Twenty' or 'Number Bonds'. These concepts will help you become even faster at mental math and prepare you for more complex addition and subtraction problems.