Quick Subtraction
📖 Learn
Quick subtraction means taking away numbers fast in your head! Just like with addition, learning subtraction tricks helps you do mental math and solve problems faster.
What Is Quick Subtraction?
Quick subtraction is taking away numbers in your head without writing them down. You learn to see numbers and know what is left right away!
Key Words to Know
- Subtract: To take away a number from another number
- Difference: The answer when you subtract
- Minus (-): The symbol that means subtract
- Take Away: Another way to say subtract
Tips for Subtracting Fast
- Count back: Start with the bigger number and count backwards
- Think addition: If 3 + 4 = 7, then 7 - 4 = 3
- Subtract from 10: Know what is left when you take away from 10
- Minus 1 or 2: These are easy - just count back one or two!
Subtracting from 10
Memorize these - they help a lot!
| 10-1=9 | 10-2=8 | 10-3=7 |
| 10-4=6 | 10-5=5 | 10-6=4 |
| 10-7=3 | 10-8=2 | 10-9=1 |
Addition and Subtraction Are Friends!
If you know an addition fact, you know a subtraction fact too!
- If 2 + 3 = 5, then 5 - 3 = 2 and 5 - 2 = 3
- If 4 + 6 = 10, then 10 - 6 = 4 and 10 - 4 = 6
💡 Examples
See how to subtract numbers quickly using different strategies.
Example 1: Counting Back
Problem: 8 - 2 = ?
Think: Start at 8, count back 2: 7, 6
Answer: 6
Example 2: Think Addition
Problem: 9 - 5 = ?
Think: What plus 5 equals 9? 4 + 5 = 9, so 9 - 5 = 4
Answer: 4
Example 3: Subtracting from 10
Problem: 10 - 7 = ?
Think: I know my subtraction from 10 facts! 10 - 7 = 3
Answer: 3
Example 4: Minus 1
Problem: 7 - 1 = ?
Think: Minus 1 means the number just before 7.
Answer: 6
Example 5: Half of a Double
Problem: 12 - 6 = ?
Think: I know 6 + 6 = 12, so 12 - 6 = 6
Answer: 6
✏️ Practice
Try to solve these subtraction problems in your head. See how fast you can go!
Problem 1
5 - 2 = ?
Show Answer
3 (count back: 5, 4, 3)
Problem 2
10 - 4 = ?
Show Answer
6 (subtract from 10: 10 - 4 = 6)
Problem 3
7 - 3 = ?
Show Answer
4 (think addition: 4 + 3 = 7)
Problem 4
9 - 1 = ?
Show Answer
8 (minus 1: the number before 9)
Problem 5
8 - 4 = ?
Show Answer
4 (half of double: 4 + 4 = 8)
Problem 6
10 - 8 = ?
Show Answer
2 (subtract from 10: 10 - 8 = 2)
Problem 7
6 - 2 = ?
Show Answer
4 (count back: 6, 5, 4)
Problem 8
11 - 5 = ?
Show Answer
6 (think addition: 5 + 6 = 11)
Problem 9
10 - 5 = ?
Show Answer
5 (half of double: 5 + 5 = 10)
Problem 10
13 - 4 = ?
Show Answer
9 (count back: 13, 12, 11, 10, 9)
✅ Check Your Understanding
Answer these questions about quick subtraction.
Question 1
What does it mean to subtract?
Show Answer
To subtract means to take away one number from another. The answer tells you how many are left. For example, if you have 7 apples and take away 3, you have 4 left (7 - 3 = 4).
Question 2
How can addition help you subtract?
Show Answer
If you know an addition fact, you can use it to subtract! For example, if you know 3 + 5 = 8, then you also know 8 - 5 = 3 and 8 - 3 = 5.
Question 3
What is 10 - 6? What strategy did you use?
Show Answer
10 - 6 = 4
You could use:
- Subtracting from 10 fact (memorized)
- Think addition: 6 + 4 = 10
- Count back from 10: 9, 8, 7, 6, 5, 4
Question 4
If you know 7 + 7 = 14, what is 14 - 7?
Show Answer
14 - 7 = 7
Since 7 + 7 = 14, taking away one 7 leaves the other 7. This is called "half of a double."
🚀 Next Steps
- Practice every day: Use subtraction in real life - how many cookies are left? How many more minutes until bedtime?
- Learn your facts from 10: Memorize all the "subtract from 10" facts.
- Connect addition and subtraction: When you learn an addition fact, practice the matching subtraction facts too.
- Time yourself: See how many subtraction problems you can solve in one minute.
- Play math games: Dice and card games can help you practice quick subtraction.
- Keep practicing: Go back to Quick Addition and practice both skills together!