Solved examples: Checking subtraction using addition (Grade 2)

📚 Quick Study Guide

• 🔢 To check subtraction using addition, you add the difference (answer) to the number you subtracted.
• ➕ If the sum equals the original number you started with, your subtraction is correct!
• 💡 Think of it like this: If $a - b = c$, then $c + b = a$.
• 📝 For example: $10 - 4 = 6$. To check, $6 + 4 = 10$. This is correct!

Practice Quiz

1. What addition problem checks the subtraction problem $15 - 7 = 8$?
   1. 8 + 7 = ?
   2. 15 + 8 = ?
   3. 7 - 8 = ?
2. What addition problem checks the subtraction problem $20 - 5 = 15$?
   1. 15 + 5 = ?
   2. 20 + 15 = ?
   3. 5 - 15 = ?
3. Check: $12 - 4 = 8$. Which addition equation verifies this?
   1. 8 + 4 = ?
   2. 12 + 8 = ?
   3. 4 - 8 = ?
4. Check: $9 - 3 = 6$. Which addition equation verifies this?
   1. 6 + 3 = ?
   2. 9 + 6 = ?
   3. 3 - 6 = ?
5. What is the correct addition equation to check $18 - 9 = 9$?
   1. 9 + 9 = ?
   2. 18 + 9 = ?
   3. 9 - 18 = ?
6. If $25 - 10 = 15$, which addition equation checks if this is correct?
   1. 15 + 10 = ?
   2. 25 + 15 = ?
   3. 10 - 15 = ?
7. Which addition checks $30 - 12 = 18$?
   1. 18 + 12 = ?
   2. 30 + 18 = ?
   3. 12 - 18 = ?