What is a Fact Family for 7?

S0-SA1-0381

Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

A fact family for 7 is a set of four related math facts (two addition and two subtraction) that use the same three numbers to make 7. It shows how addition and subtraction are opposite operations. For the number 7, we look for pairs of numbers that add up to 7.

Simple Example

Quick Example

Imagine you have 7 laddus. If your friend has 3 laddus and you have 4 laddus, together you have 7 laddus (3 + 4 = 7). This also means if you start with 7 laddus and give 3 away, you have 4 left (7 - 3 = 4). These numbers (3, 4, 7) form a fact family.

Worked Example

Step-by-Step

Let's find a fact family for 7 using the numbers 2, 5, and 7.
---1. Start with the two numbers that add up to 7. Here, 2 + 5 = 7.
---2. Reverse the order of the adding numbers. So, 5 + 2 = 7.
---3. Now, for subtraction, start with the largest number (7). Subtract one of the smaller numbers. So, 7 - 2 = 5.
---4. Finally, subtract the other smaller number from 7. So, 7 - 5 = 2.
---The fact family for 7 using 2, 5, and 7 is: 2 + 5 = 7, 5 + 2 = 7, 7 - 2 = 5, and 7 - 5 = 2.

Why It Matters

Understanding fact families builds a strong foundation for mental math and problem-solving. It helps you quickly solve addition and subtraction problems without counting. This skill is crucial for careers like a shopkeeper managing inventory, an engineer calculating measurements, or even a cricketer keeping track of scores.

Common Mistakes

MISTAKE: Using numbers that don't add up to 7 for an addition fact | CORRECTION: Always ensure the two smaller numbers in your fact family add up to the target number, which is 7 in this case.

MISTAKE: Not including all four related facts (two addition, two subtraction) | CORRECTION: Remember a complete fact family always has two addition facts and two subtraction facts using the same three numbers.

MISTAKE: Subtracting a larger number from a smaller one in the subtraction facts | CORRECTION: For subtraction facts in a fact family, always start with the largest number (7) and subtract one of the smaller numbers.

Practice Questions

Try It Yourself

QUESTION: Which set of numbers forms a fact family for 7? (a) 1, 6, 7 | (b) 2, 4, 7 | (c) 3, 3, 7 | (d) 1, 7, 8 | ANSWER: (a) 1, 6, 7

QUESTION: Write the complete fact family for 7 using the numbers 0, 7, and 7. | ANSWER: 0 + 7 = 7, 7 + 0 = 7, 7 - 0 = 7, 7 - 7 = 0

QUESTION: If you know that 3 + 4 = 7, what are the other three facts in this fact family? | ANSWER: 4 + 3 = 7, 7 - 3 = 4, 7 - 4 = 3

MCQ

Quick Quiz

Which of these is NOT part of the fact family for 7, if the numbers involved are 1, 6, and 7?

1 + 6 = 7

7 - 1 = 6

6 - 1 = 5

7 - 6 = 1

The Correct Answer Is:

Option C (6 - 1 = 5) uses numbers 6, 1, and 5. The number 5 is not part of the fact family for 7 involving 1, 6, and 7. All other options correctly use only 1, 6, and 7 to form facts.

Real World Connection

In the Real World

When you're sharing a packet of 7 biscuits with friends, you use fact families without even realizing it! If you give 3 to one friend, you know you have 4 left (7 - 3 = 4). If you then find 4 more in your bag, you know you have 7 again (3 + 4 = 7). This basic math helps in daily tasks like managing pocket money or dividing tasks.

Key Vocabulary

Key Terms

FACT FAMILY: A set of four related math facts using the same three numbers | ADDITION: Combining two or more numbers to find their sum | SUBTRACTION: Taking one number away from another to find the difference | SUM: The result of adding two or more numbers | DIFFERENCE: The result of subtracting one number from another

What's Next

What to Learn Next

Great job understanding fact families for 7! Next, you can explore fact families for other numbers like 8, 9, or 10. This will strengthen your number sense and prepare you for more complex addition and subtraction problems, like adding larger numbers or solving word problems.