Add and subtract numbers up to 20
key notes :
➕ Addition up to 20
Addition means putting numbers together to find the total.
Use the plus sign (+).
Example: 7 + 5 = 12
Count using:
- Fingers ✋
- Objects (blocks, beads)
- Number line ➡️
Start from the bigger number and count forward.
Practice number bonds (e.g., 10 + 6 = 16).
Learn simple facts like:
- 10 + 5 = 15
- 9 + 1 = 10
➖ Subtraction up to 20
Subtraction means taking away or finding how many are left.
Use the minus sign (−).
Example: 15 − 6 = 9
Use methods:
- Cross out objects ❌
- Count backward ⬅️
- Number line
Think: “What is left after taking away?”
🔄 Relationship Between Addition & Subtraction
They are opposites (inverse operations).
Example:
- 8 + 4 = 12
- 12 − 4 = 8
Helps to check answers.
🧠 Strategies to Learn Easily
Use making 10 strategy:
- Example: 8 + 5 → (8 + 2 = 10, then 10 + 3 = 13)
Break numbers:
- 14 − 6 → (14 − 4 = 10, then 10 − 2 = 8)
Practice mental math for quick answers.
✏️ Word Problems
Look for clue words:
- Addition: total, together, more
- Subtraction: left, fewer, take away
Example:
- “Ravi has 9 apples and gets 5 more. How many now?” → 9 + 5 = 14
Learn with an example
🎈 Subtract. 14 – 5=_____
- You can count back to subtract. Start from 14 and count back 5:
- 14, 13, 12, 11, 10, 9
- 14 – 5=9
- The difference is 9.
🎈Add. 12 + 7=____
- You can count up to add. It is easier to start with a larger number. Start from 12 and count up to 7:
- 12, 13, 14, 15, 16, 17, 18, 19
- 12 + 7=19
- The sum is 19.
🎈 Add: 1 + 1=___
- You can count up to add. Start from 1 and count up to 1:
- 1, 2
- 1+1= 2
- The sum is 2.
Let’s practice!🖊️
