Subtraction: Taking away one number from another to find the difference
Note: Subtraction finds how many are left when we take away a certain amount.
- Start with the first number (minuend)
- Take away the second number (subtrahend)
- Count how many are left (difference)
We have 8 objects: ⭐⭐⭐⭐⭐⭐⭐⭐
Remove 3 objects: ⭐⭐⭐⭐⭐ (⭐⭐⭐)
5 objects remain: ⭐⭐⭐⭐⭐
8 - 3 = 5
• Subtraction: Take away the subtrahend from the minuend
• Counting: Count how many remain after taking away
• Practice Tip: Use fingers or objects to visualize the subtraction
- 6 - 2 = 4 - Practice with smaller numbers
- 9 - 4 = 5 - Practice with different combinations
- 7 - 1 = 6 - Practice with single subtraction
- Subtraction is the opposite of addition
- You can check by adding: 5 + 3 = 8 ✓
- Always start with the bigger number when subtracting
Q: What if I subtract a bigger number from a smaller one?
A: At this level, we only subtract smaller numbers from bigger numbers.
Q: How do I know which number is bigger?
A: The first number (minuend) should be bigger than the second number (subtrahend).
Number bond: Shows how numbers are related in addition and subtraction
Note: Number bonds help us understand that 7 can be broken into 4 and 3.
- Think about what number goes with 4 to make 7
- Use the relationship: 4 + ? = 7
- Since 4 + 3 = 7, then 7 - 4 = 3
We want to break apart 7
So 7 = 4 + ?
4 + 3 = 7, so 7 - 4 = 3
7 - 4 = 3
• Number bond: 7 can be split into 4 and 3
• Relationship: Addition and subtraction are inverse operations
• Practice Tip: Know number bonds to 10 to help with subtraction
- 6 = 4 + 2, so 6 - 4 = 2
- 8 = 5 + 3, so 8 - 5 = 3
- 9 = 6 + 3, so 9 - 6 = 3
- Number bonds help you see subtraction as "what's missing?"
- Know your number bonds to 10: 1+9, 2+8, 3+7, 4+6, 5+5
- Use addition to check: 3 + 4 = 7 ✓
Q: What are number bonds?
A: Number bonds show how a number can be split into parts. For example, 7 can be 4 and 3.
Q: How do number bonds help with subtraction?
A: They help you think "what number added to 4 gives me 7?" which leads to 7 - 4 = 3.
Counting back: Starting from the first number and counting backwards by the second number
Note: This is a mental math strategy for subtraction.
- Start at the first number (9)
- Count backwards by the second number (2)
- Land on the answer (7)
Begin counting: 9
9 → 8 → 7 (count 2 steps back)
We land on 7
9 - 2 = 7
• Counting back: Move backwards on the number line
• Strategy: This helps with mental math
• Practice Tip: Use fingers or number line to visualize counting back
- 8 - 3: Start at 8, count back 3 → 8, 7, 6, 5 → Answer: 5
- 6 - 1: Start at 6, count back 1 → 6, 5 → Answer: 5
- 10 - 4: Start at 10, count back 4 → 10, 9, 8, 7, 6 → Answer: 6
- Count back slowly and carefully
- This strategy works best for small numbers being subtracted
- Use your fingers to help keep track of counting back
Q: When should I use counting back?
A: Use it for small subtrahends (like subtracting 1, 2, or 3).
Q: What if I count back too far?
A: Start over and count more carefully, or use objects to help.
Fact family: A group of related addition and subtraction facts using the same numbers
Note: The numbers 5, 3, and 8 form a fact family: 5+3=8, 3+5=8, 8-3=5, 8-5=3.
- Recognize that 5, 3, and 8 are in the same fact family
- If 5 + 3 = 8, then 8 - 3 = 5 (the other addend)
- Verify: 5 + 3 = 8 and 8 - 3 = 5
Numbers 5, 3, and 8 are related
If 5 + 3 = 8, then 8 - 3 = 5
5 + 3 = 8 ✓ and 8 - 3 = 5 ✓
8 - 3 = 5
• Fact family: Addition and subtraction facts using same numbers
• Inverse operations: Addition and subtraction undo each other
• Practice Tip: Know fact families to build fluency
- If 4 + 2 = 6, then 6 - 2 = 4
- If 7 + 1 = 8, then 8 - 1 = 7
- If 6 + 3 = 9, then 9 - 3 = 6
- Fact families show the connection between addition and subtraction
- Knowing one fact helps you know three others
- Use fact families to check your work
Q: What is a fact family?
A: A group of related addition and subtraction facts using the same three numbers.
Q: How do fact families help with subtraction?
A: If you know an addition fact, you automatically know the related subtraction facts.
Missing number: Finding the unknown value in a subtraction equation
Note: We need to find what number subtracted from 6 gives 2.
- Think: "What number taken from 6 leaves 2?"
- Use addition: 2 + ? = 6
- Since 2 + 4 = 6, then 6 - 4 = 2
We need to find what number subtracted from 6 equals 2
Instead of subtracting, we add: 2 + ? = 6
2 + 4 = 6, so the missing number is 4
6 - 4 = 2 ✓
The missing number is 4
• Inverse operations: Addition and subtraction undo each other
• Missing number: Use the inverse operation to find it
• Verification: Always check your answer
• Practice Tip: Turn subtraction problems with missing numbers into addition problems
- 8 - ? = 5 → 5 + ? = 8 → ? = 3
- ? - 3 = 4 → 3 + 4 = ? → ? = 7
- 9 - ? = 1 → 1 + ? = 9 → ? = 8
- Turn subtraction with missing numbers into addition problems
- Always check your answer by substituting back
- Use number lines or objects to visualize the problem
Q: How do I solve problems with missing numbers?
A: Use the inverse operation. If subtracting, add the known numbers to find the missing one.
Q: What if the missing number is the first one?
A: For ? - 3 = 4, add the two known numbers: 3 + 4 = 7, so ? = 7.