What is a Number Family (of 6)?

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Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

A Number Family, also called a Fact Family, shows how three numbers are related through addition and subtraction. For a number like 6, its family includes all the addition and subtraction facts that use those three specific numbers.

Simple Example

Quick Example

Imagine you have 6 ladoos. You eat 2 ladoos. How many are left? 4 ladoos. This means 6, 2, and 4 are a number family because 2 + 4 = 6, 4 + 2 = 6, 6 - 2 = 4, and 6 - 4 = 2. They all 'belong' together!

Worked Example

Step-by-Step

Let's find the number family for 6, using the numbers 6, 1, and 5.

Step 1: Start with an addition fact. If you have 1 rupee and your friend gives you 5 rupees, you now have 6 rupees. So, 1 + 5 = 6.

---Step 2: Reverse the addition fact. It doesn't matter which number you add first. If your friend has 5 rupees and you give 1 rupee, it's still 6 rupees. So, 5 + 1 = 6.

---Step 3: Now, for subtraction. Start with the largest number (the total). If you have 6 rupees and spend 1 rupee, how much is left? 5 rupees. So, 6 - 1 = 5.

---Step 4: Finally, subtract the other number. If you have 6 rupees and spend 5 rupees, how much is left? 1 rupee. So, 6 - 5 = 1.

---Answer: The number family for 6 (using 1 and 5) is: 1 + 5 = 6, 5 + 1 = 6, 6 - 1 = 5, and 6 - 5 = 1.

Why It Matters

Understanding number families helps you solve math problems faster and makes mental calculations easier. This skill is crucial for careers like accounting, where you track money, or even for a shopkeeper who needs to quickly calculate change for customers.

Common Mistakes

MISTAKE: Using numbers that don't belong in the family (e.g., for 6, using 2 and 3 because 2+3=5, not 6). | CORRECTION: Always make sure the two smaller numbers add up to the largest number in the family.

MISTAKE: Forgetting to write all four facts (two addition, two subtraction). | CORRECTION: Remember that a complete number family always has four facts, like four members in a small family.

MISTAKE: Confusing the largest number (the sum) with one of the parts in subtraction. | CORRECTION: The largest number is always the first number in a subtraction fact for a number family.

Practice Questions

Try It Yourself

QUESTION: Write the number family for 6, using the numbers 6, 3, and 3. | ANSWER: 3 + 3 = 6, 6 - 3 = 3

QUESTION: If you know 2 + 4 = 6, what are the other three facts in this number family? | ANSWER: 4 + 2 = 6, 6 - 2 = 4, 6 - 4 = 2

QUESTION: Your mom gave you 6 samosas. You ate some, and 2 were left. What number family describes this situation? Write all four facts. | ANSWER: The numbers are 6, 2, and 4 (because 6 - 2 = 4). The family is: 4 + 2 = 6, 2 + 4 = 6, 6 - 2 = 4, 6 - 4 = 2

MCQ

Quick Quiz

Which set of facts correctly forms a number family for 6, using the numbers 6, 4, and 2?

2 + 4 = 6, 4 - 2 = 2, 6 - 4 = 2

2 + 4 = 6, 4 + 2 = 6, 6 - 4 = 2, 6 - 2 = 4

2 + 6 = 8, 6 - 2 = 4, 4 + 2 = 6

6 + 2 = 8, 6 - 4 = 2, 4 + 2 = 6

The Correct Answer Is:

Option B includes all four correct addition and subtraction facts relating the numbers 2, 4, and 6. The other options either miss facts or use incorrect relationships.

Real World Connection

In the Real World

When a shopkeeper gives you change after you buy something for 4 rupees from a 6-rupee note, they are using a number family (6 - 4 = 2 rupees change). Similarly, when cricket commentators talk about a team needing 6 runs with 2 wickets down, they are implicitly using these number relationships.

Key Vocabulary

Key Terms

NUMBER FAMILY: A set of addition and subtraction facts using three related numbers. | FACT FAMILY: Another name for a number family. | ADDITION FACT: A number sentence showing two numbers combined to make a total. | SUBTRACTION FACT: A number sentence showing how taking one number from another leaves a difference. | SUM: The total when two or more numbers are added.

What's Next

What to Learn Next

Great job understanding number families! Next, you can explore number families for larger numbers, or learn about related concepts like skip counting and multiplication facts. These build on your understanding of how numbers work together.