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What is a Number Family of 11?
Grade Level:
Pre-School – Class 2
All domains without exception
Definition
What is it?
A 'Number Family of 11' includes all the pairs of whole numbers that add up to exactly 11. It helps us understand how different numbers combine to make 11, using both addition and subtraction.
Simple Example
Quick Example
Imagine you need to score 11 runs in cricket to win a match. If one batsman scores 5 runs, how many runs does the other batsman need to score? The pair (5, 6) is part of the number family of 11 because 5 + 6 = 11.
Worked Example
Step-by-Step
Let's find all the pairs of whole numbers that make up the number family of 11.
Step 1: Start with 0. What number added to 0 gives 11? 0 + 11 = 11. So, (0, 11) is a pair.
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Step 2: Move to 1. What number added to 1 gives 11? 1 + 10 = 11. So, (1, 10) is a pair.
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Step 3: Move to 2. What number added to 2 gives 11? 2 + 9 = 11. So, (2, 9) is a pair.
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Step 4: Continue this pattern: 3 + 8 = 11, so (3, 8) is a pair.
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Step 5: 4 + 7 = 11, so (4, 7) is a pair.
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Step 6: 5 + 6 = 11, so (5, 6) is a pair.
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Step 7: We stop at 5 because the next pair would be (6, 5), which is just the reverse of (5, 6).
Answer: The number family of 11 includes the pairs: (0, 11), (1, 10), (2, 9), (3, 8), (4, 7), (5, 6).
Why It Matters
Understanding number families builds a strong foundation for mental math and problem-solving. It's crucial for careers like banking, where you quickly calculate totals, or even in sports analytics, predicting scores.
Common Mistakes
MISTAKE: Forgetting to include 0 and the number itself (e.g., 0 + 11). | CORRECTION: Always start with 0 and go up, ensuring you cover all whole number pairs.
MISTAKE: Including duplicate pairs (e.g., listing both (3, 8) and (8, 3) separately as unique pairs). | CORRECTION: Once you reach the middle (like 5+6), the pairs start repeating in reverse order, so you don't need to list them again.
MISTAKE: Confusing number families with multiplication facts. | CORRECTION: Remember, number families are about addition and subtraction, not multiplication.
Practice Questions
Try It Yourself
QUESTION: Which number completes the pair for the number family of 11: (7, __)? | ANSWER: 4 (because 7 + 4 = 11)
QUESTION: Riya has 3 laddus. Her friend gives her some more, and now she has 11 laddus in total. How many laddus did her friend give her? | ANSWER: 8 laddus (because 3 + 8 = 11)
QUESTION: List all the unique pairs of whole numbers that form the number family of 11. | ANSWER: (0, 11), (1, 10), (2, 9), (3, 8), (4, 7), (5, 6)
MCQ
Quick Quiz
Which of these pairs does NOT belong to the number family of 11?
(1, 10)
(6, 5)
(4, 6)
(2, 9)
The Correct Answer Is:
C
Option C (4, 6) adds up to 10, not 11. All other options add up to 11, making them part of the number family of 11.
Real World Connection
In the Real World
When you pay for something using UPI, you often need to quickly check if the total amount adds up correctly. For example, if you buy chai for 5 rupees and a biscuit packet for 6 rupees, you know the total is 11 rupees (5 + 6 = 11), a direct application of the number family of 11.
Key Vocabulary
Key Terms
Number Family: a set of numbers related by addition and subtraction | Whole Numbers: counting numbers starting from 0 (0, 1, 2, 3...) | Addition: combining numbers to find a total | Subtraction: taking one number away from another
What's Next
What to Learn Next
Great job with the number family of 11! Next, you can explore the 'Number Family of 10' or 'Number Family of 12'. This will strengthen your number sense and make bigger calculations much easier.
