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What is a Fact Family for 11?
Grade Level:
Pre-School – Class 2
All domains without exception
Definition
What is it?
A fact family for 11 is a group of four related math facts (two addition and two subtraction) that use the same three numbers to make 11. It shows how addition and subtraction are opposite operations.
Simple Example
Quick Example
Imagine you have 7 laddus and your friend gives you 4 more. Now you have 11 laddus. This gives us an addition fact: 7 + 4 = 11. If you start with 11 laddus and eat 4, you are left with 7. This is a subtraction fact: 11 - 4 = 7. These are part of the fact family for 11 using the numbers 4, 7, and 11.
Worked Example
Step-by-Step
Let's find the fact family for 11 using the numbers 5 and 6.
Step 1: Identify the three numbers. We have 5, 6, and 11.
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Step 2: Write the first addition fact. Add the two smaller numbers to get the largest number.
5 + 6 = 11
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Step 3: Write the second addition fact. Swap the order of the two smaller numbers.
6 + 5 = 11
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Step 4: Write the first subtraction fact. Start with the largest number and subtract one of the smaller numbers.
11 - 5 = 6
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Step 5: Write the second subtraction fact. Start with the largest number and subtract the other smaller number.
11 - 6 = 5
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Answer: The fact family for 11 using 5, 6, and 11 is: 5 + 6 = 11, 6 + 5 = 11, 11 - 5 = 6, and 11 - 6 = 5.
Why It Matters
Understanding fact families helps you learn basic addition and subtraction much faster. It builds a strong foundation for mental math and solving everyday problems. This skill is useful for careers like shopkeepers who quickly calculate change or engineers who need to understand relationships between numbers.
Common Mistakes
MISTAKE: Using numbers that don't add up to 11 for the addition facts, or don't subtract from 11 to get the other number. | CORRECTION: Always check that the three numbers you choose for your fact family correctly relate to 11 through addition and subtraction.
MISTAKE: Forgetting to write all four facts (two addition and two subtraction). | CORRECTION: Remember that a complete fact family always has four members. Think of it as a set of rules for the three numbers.
MISTAKE: Confusing the largest number in the family. | CORRECTION: In a fact family for 11, 11 will always be the largest number. It's the sum in addition and the starting number (minuend) in subtraction.
Practice Questions
Try It Yourself
QUESTION: Write the fact family for 11 using the numbers 8 and 3. | ANSWER: 8 + 3 = 11, 3 + 8 = 11, 11 - 8 = 3, 11 - 3 = 8
QUESTION: If you know that 11 - 7 = 4, what are the other three facts in this family? | ANSWER: 11 - 4 = 7, 7 + 4 = 11, 4 + 7 = 11
QUESTION: A vegetable seller has 11 kg of potatoes. He sells some and has 6 kg left. What addition fact and what subtraction fact describe this situation, and what are the other two facts in this family? | ANSWER: 11 - 6 = 5 (he sold 5 kg), 5 + 6 = 11. The other two facts are 6 + 5 = 11 and 11 - 5 = 6.
MCQ
Quick Quiz
Which of these is NOT part of the fact family for 11 using the numbers 2, 9, and 11?
9 + 2 = 11
11 - 9 = 2
11 + 2 = 13
2 + 9 = 11
The Correct Answer Is:
C
Option C (11 + 2 = 13) is incorrect because 11 is the largest number in this fact family, so you cannot add to it to form a fact within this family. The other options correctly show relationships between 2, 9, and 11.
Real World Connection
In the Real World
When you're sharing a packet of 11 biscuits with friends, you might give 5 to one friend and have 6 left. This shows a fact family: 5 + 6 = 11, 6 + 5 = 11, 11 - 5 = 6, and 11 - 6 = 5. Even when calculating how much money you need for a ₹11 auto ride if you only have ₹7, you're using this concept to find the missing amount.
Key Vocabulary
Key Terms
FACT FAMILY: A group of related math facts using the same three numbers | ADDITION: Combining numbers to find a total | SUBTRACTION: Taking one number away from another to find the difference | SUM: The answer to an addition problem | DIFFERENCE: The answer to a subtraction problem
What's Next
What to Learn Next
Now that you understand fact families for 11, try exploring fact families for other numbers like 12 or 15. This will strengthen your understanding of how numbers relate to each other through addition and subtraction, which is key for more complex math later on!
