What is a Fact Family for 19?

S0-SA1-1318

Grade Level:

Pre-School – Class 2

All domains without exception

Definition

What is it?

A fact family for 19 is a group of four related math facts (two addition and two subtraction) that use the same three numbers. These numbers show how addition and subtraction are opposite operations.

Simple Example

Quick Example

Imagine you have 7 laddus and your friend gives you 12 more. Now you have 19 laddus. This gives us an addition fact: 7 + 12 = 19. If you start with 19 laddus and give 7 away, you have 12 left. This is a subtraction fact: 19 - 7 = 12.

Worked Example

Step-by-Step

Let's find the fact family for the numbers 7, 12, and 19.

1. **Identify the three numbers:** The numbers are 7, 12, and 19. Remember, the largest number (19) is the sum in addition and the starting number in subtraction.

2. **First Addition Fact:** Add the two smaller numbers to get the largest number. 7 + 12 = 19.

3. **Second Addition Fact:** Swap the order of the two smaller numbers. The sum remains the same. 12 + 7 = 19.

4. **First Subtraction Fact:** Start with the largest number and subtract one of the smaller numbers. The answer will be the other smaller number. 19 - 7 = 12.

5. **Second Subtraction Fact:** Start with the largest number and subtract the other smaller number. The answer will be the first smaller number. 19 - 12 = 7.

So, the fact family for 7, 12, and 19 is: 7 + 12 = 19, 12 + 7 = 19, 19 - 7 = 12, and 19 - 12 = 7.

Why It Matters

Understanding fact families helps you see the connection between addition and subtraction, which is super important for faster mental math. It's like knowing two sides of the same coin! This skill is useful for shopkeepers calculating change, engineers checking measurements, and even game developers creating scoring systems.

Common Mistakes

MISTAKE: Using numbers not from the family (e.g., for 7, 12, 19, writing 7 + 10 = 17) | CORRECTION: Always use only the three numbers given for the fact family.

MISTAKE: Not having the largest number as the sum in addition or the starting number in subtraction (e.g., 7 - 19 = 12) | CORRECTION: In addition, the largest number is always the answer. In subtraction, the largest number is always what you start with.

MISTAKE: Forgetting to write all four facts (two addition and two subtraction) | CORRECTION: A complete fact family always has four related facts.

Practice Questions

Try It Yourself

QUESTION: Write the fact family for the numbers 5, 14, and 19. | ANSWER: 5 + 14 = 19, 14 + 5 = 19, 19 - 5 = 14, 19 - 14 = 5

QUESTION: If 19 - 8 = 11 is one fact, what are the other three facts in its family? | ANSWER: 8 + 11 = 19, 11 + 8 = 19, 19 - 11 = 8

QUESTION: Reena bought 19 rotis. She ate some and gave 6 to her brother. She had 13 left. Write the fact family that describes this situation. | ANSWER: 6 + 13 = 19, 13 + 6 = 19, 19 - 6 = 13, 19 - 13 = 6

MCQ

Quick Quiz

Which set of facts forms a complete fact family for the numbers 6, 13, and 19?

6 + 13 = 19, 13 + 6 = 19, 19 - 6 = 13

6 + 13 = 19, 13 + 6 = 19, 19 - 6 = 13, 19 - 13 = 6

6 + 13 = 19, 19 - 6 = 13, 19 - 13 = 6

6 + 13 = 19, 19 - 13 = 6, 19 + 6 = 25

The Correct Answer Is:

Option B includes all four correct facts (two addition and two subtraction) using only the numbers 6, 13, and 19. Other options are missing facts or include incorrect facts.

Real World Connection

In the Real World

When a 'kirana' store owner counts items, like 19 packets of biscuits, and sells 7, they quickly know 12 are left (19 - 7 = 12). If they then get 7 more, they know they are back to 19 (12 + 7 = 19). This quick mental math, based on fact families, helps them manage stock and calculate sales efficiently.

Key Vocabulary

Key Terms

Fact Family: A group of four related math facts using the same three numbers | Addition: The process of combining numbers | Subtraction: The process of taking one number away from another | Sum: The result of an addition problem | Difference: The result of a subtraction problem

What's Next

What to Learn Next

Now that you understand fact families for addition and subtraction, you can explore fact families for multiplication and division. This will help you see how these operations are also related and build a stronger foundation for algebra!