Solved Exercises on Understanding Subtraction in Grade 1

Master understanding subtraction: basic concepts, visual representation, and problem solving through these 5 detailed exercises.

Solution: Exercises 1 to 3
1 Basic Subtraction Concepts
Exercise 1
Solve: 7 - 3 = ? using the "taking away" method
Definition:

Subtraction: Taking away a number from another number

Taking Away: Removing objects from a group

Minus Sign (-): Symbol for subtraction operation

Taking Away Method:
  1. Start with the first number (7)
  2. Take away the second number (3)
  3. Count what's left
  4. Write the complete equation
Start With
-
Take Away
=
Left Over
Step 1: Start with 7 objects

We have 7 dots: ●●●●●●●

Step 2: Take away 3 objects

Cross out 3 dots: ❌❌❌

Step 3: Count what's left

Remaining dots: ●●●● (4 dots)

Step 4: Write the equation

7 - 3 = 4

7 - 3 = 4
Final answer:

7 - 3 = 4

Applied rules:

• Taking away: Remove objects from the starting amount

• Counting remainder: Count what's left after taking away

• Subtraction symbol: Use minus sign (-) for subtraction

2 Subtraction as Finding Difference
Exercise 2
Solve: 9 - 4 = ? using the "finding difference" method
Definition:

Finding Difference: How many more or less one number is than another

Comparison: Looking at the gap between two numbers

Start
9
→
Take Away
→
Remainder
5
Step 1: Start with 9

We have 9 objects

Step 2: Take away 4

Remove 4 objects

Step 3: Count remaining

How many are left? 5 objects

Step 4: State the difference

The difference between 9 and 4 is 5

9 - 4 = 5
Final answer:

9 - 4 = 5

Applied rules:

• Difference concept: Subtraction shows the gap between numbers

• Comparison: How much more one number is than another

• Removal method: Take away to see what remains

3 Subtraction on Number Line
Exercise 3
Solve: 8 - 3 = ? using a number line
Definition:

Number Line: A straight line with numbers at equal intervals

Backward Movement: Moving left on the number line for subtraction

Start At
8
←
Move Back
→
Land At
5
Step 1: Start at 8

Place your finger on 8 on the number line

Step 2: Move backward 3 steps

Count back: 7, 6, 5

Step 3: Land on the answer

You land on 5

Step 4: Write the equation

8 - 3 = 5

8 - 3 = 5
Final answer:

8 - 3 = 5

Applied rules:

• Direction rule: Subtraction moves left on number line

• Step counting: Count backward the number of steps to subtract

• Landing point: Final position is the answer

Rules and methods, laws,...
\(7 - 3 = 4\)
Subtraction Concepts
Taking Away
Method
Remove objects
Finding
Difference
Compare numbers
Number Line
Rule
Move left for subtraction
Key definitions:

Subtraction: The operation of taking away one number from another

Minuend: The first number in a subtraction problem (what you start with)

Subtrahend: The second number in a subtraction problem (what you take away)

Difference: The result of a subtraction problem

Complete methodology:
  1. Identify components: Recognize minuend, subtrahend, and operation
  2. Choose strategy: Taking away, finding difference, or number line
  3. Execute calculation: Perform the subtraction
  4. Verify answer: Check through addition (subtrahend + difference = minuend)
  5. Record result: Write the complete equation
Tip 1: Remember: subtraction means "take away" or "find the difference".
Tip 2: Use your fingers or objects to visualize the process.
Tip 3: On number lines, subtraction moves left (opposite of addition).
Tip 4: Check your answer: add the result to the number you took away.
Common errors: Going in wrong direction, forgetting to count all taken away.
Key concepts: Understanding that subtraction decreases quantity.
Rules to remember:

• Direction rule: Subtraction moves left on number line

• Verification: Difference + Subtrahend = Minuend

• Decreasing: Subtraction results in a smaller number

• Order matters: 7 - 3 ≠ 3 - 7

Subtraction Facts (within 10)
5 - 1 = 4
6 - 2 = 4
7 - 3 = 4
8 - 4 = 4
9 - 5 = 4
6 - 1 = 5
7 - 2 = 5
8 - 3 = 5
9 - 4 = 5
10 - 5 = 5
7 - 1 = 6
8 - 2 = 6
9 - 3 = 6
10 - 4 = 6
Solution: Exercises 4 to 5
4 Word Problems with Subtraction
Exercise 4
Sarah has 8 cookies. She eats 3 cookies. How many cookies does Sarah have left?
Definition:

Word Problem: A math question written in story form

Subtraction Keywords: Words that indicate subtraction ("eat", "left", "remain")

Step 1: Identify what we start with

Sarah starts with 8 cookies

Step 2: Identify what's taken away

She eats 3 cookies

Step 3: Find the keyword

"Eats" means we take away, "left" asks for the remainder

Step 4: Set up the equation

8 - 3 = 5

Step 5: Write the answer

Sarah has 5 cookies left

8 - 3 = 5
Final answer:

Sarah has 5 cookies left

Applied rules:

• Keyword identification: "Eats" indicates subtraction

• Context understanding: Something is being removed from a group

• Problem translation: Convert story to mathematical equation

5 Mixed Subtraction Problems
Exercise 5
Solve: 10 - 7 = ? and 6 - 4 = ? using different methods
Definition:

Mixed Problems: Different subtraction problems to practice various methods

Method Flexibility: Using different strategies for different problems

Step 1: Solve 10 - 7 using taking away

Start with 10, take away 7: 10 - 7 = 3

Step 2: Solve 6 - 4 using number line

Start at 6, move back 4: 6 → 5 → 4 → 3 → 2, so 6 - 4 = 2

Step 3: Verify both answers

Check: 7 + 3 = 10 ✓ and 4 + 2 = 6 ✓

Step 4: Notice the patterns

Subtraction always results in a smaller number

10 - 7 = 3
6 - 4 = 2
Final answer:

10 - 7 = 3 and 6 - 4 = 2

Applied rules:

• Method selection: Choose the most efficient strategy

• Verification: Add back to check your subtraction

• Consistency: Same rules apply to all subtraction problems

Understanding Subtraction - Complete Guide
\(7 - 3 = 4\)
Subtraction Fundamentals
Key definitions:

Subtraction: The mathematical operation of taking away one quantity from another

Minuend: The number from which another number is subtracted (the starting amount)

Subtrahend: The number that is subtracted (the amount taken away)

Difference: The result of a subtraction problem (what remains)

Complete methodology:
  1. Recognition: Identify that subtraction is needed
  2. Component identification: Determine minuend and subtrahend
  3. Strategy selection: Choose the most appropriate method
  4. Execution: Perform the subtraction operation
  5. Verification: Check the answer using inverse operation
  6. Communication: Express the result clearly
Tip 1: Remember: subtraction always makes numbers smaller.
Tip 2: Use multiple methods to verify your answers.
Tip 3: Practice with real objects to build understanding.
Tip 4: Check your work: add the difference back to the subtrahend.
Visual benefits: Concrete objects and visual aids make abstract concepts understandable.
Real-world connection: Subtraction appears in many daily life situations.
Essential formulas:

• Subtraction equation: Minuend - Subtrahend = Difference

• Verification: Difference + Subtrahend = Minuend

• Number line rule: Subtraction moves left

• Property: Subtraction is not commutative (a - b ≠ b - a)

Subtraction Understanding Workflow

📊
Step-by-Step Process
1
Identify
2
Components
3
Choose Method
4
Subtract
5
Verify
Subtraction Keywords

take away

left

remain

difference

less

Practice Makes Perfect!

Questions & Answers

Question: Why is subtraction different from addition? They seem like opposites.

Answer: You're absolutely right! Addition and subtraction are like opposite actions. Here's how they differ:

  • Addition: Puts things together, makes numbers bigger
  • Subtraction: Takes things away, makes numbers smaller
  • Direction: Addition moves right on number line, subtraction moves left
  • Relationship: They undo each other (if 5 + 3 = 8, then 8 - 3 = 5)

Think of it like walking: addition is walking forward, subtraction is walking backward!

Example: If you have 5 apples and add 2 more, you have 7. If you start with 7 and take away 2, you get back to 5.

Question: My child sometimes subtracts the wrong way (like 3 - 7 instead of 7 - 3). How can I help them understand?

Answer: This is very common! Here's how to help:

  • Visual representation: Show that you can't take away more than you have
  • Real objects: Use actual items to demonstrate "you can't take 7 from 3"
  • Language: "Start with" the first number, "take away" the second
  • Story problems: Use contexts that make sense

For 7 - 3: "You have 7 cookies, you eat 3, how many left?"

Emphasize that subtraction usually results in a smaller number than what you started with!

Question: Why do we need to check our subtraction answers? Can't we just trust them?

Answer: Checking is like having a safety net! Here's how to check subtraction:

  • Add back: If 8 - 3 = 5, then 5 + 3 should equal 8
  • Count up: From your answer, count up by the number you took away
  • Estimate: Make sure your answer makes sense

Example: 9 - 4 = 5. Check: 5 + 4 = 9 ✓

Checking helps you catch mistakes and builds confidence in your math skills!

It's always better to be sure than sorry!

Question: What are some fun ways to practice subtraction?

Answer: Fun practice makes learning stick! Here are engaging activities:

  • Cookie math: Start with 10 cookies, eat some, count what's left
  • Toy problems: Use action figures or cars for subtraction stories
  • Number line walks: Walk forward for addition, backward for subtraction
  • Game creation: Make up subtraction stories with favorite characters

Engaging activities:

  • Play "Subtraction War" with playing cards
  • Use dice to generate random problems
  • Create subtraction songs or rhymes
  • Build with blocks, then take some away

The key is making practice feel like play, not work!