Subtracting 1
key notes :
🍎 Meaning of Subtracting 1
- Subtracting 1 means taking away one object from a group.
- Example: If you have 5 apples and take away 1 apple, you have 4 apples left.
🔢 Subtracting 1 Makes the Number Smaller
When we subtract 1, the number becomes one less.
Example:
- 7 − 1 = 6
- 3 − 1 = 2
📉 “One Less Than”
The answer is the number that comes just before it on the number line.
Example:
- One less than 9 is 8.
📏 Using a Number Line
Students can jump back one step to subtract 1.
Example:
Start at 6, jump back 1 step, land on 5 → 6 − 1 = 5.
🍭 Using Pictures or Objects
Kids can use:
- 🍬 Candies
- 🧱 Blocks
- 🧸 Toys
- ✏️ Pencils
Take away one item to see the answer.
Example:
🎈🎈🎈🎈 → take away one 🎈 → 🎈🎈🎈 (4 − 1 = 3)
🧠 Quick Mental Trick
Just say the number that comes before.
Example:
What is 10 − 1?
Think: What number comes before 10? → 9
🧩 Subtracting 1 Helps With Bigger Math
Learning to subtract 1 helps students later subtract bigger numbers, learn patterns, and improve mental math.
Learn with an example
✏️ Subtract. 2–1=
- You can count back to find 2–1. Start at 2 and count back 1 time.
- You end at 1.
- 2–1=1
✏️ Subtract. 7–1=
- You can count back to find 7–1. Start at 7 and count back 1 time.
- You end at 6.
- 7–1=6
✏️ Subtract. 4–1=
- You can count back to find 4–1. Start at 4 and count back 1 time.
- You end at 3.
- 4–1=3
Let’s practice!
