Meena's school collected 347 books in the first week and 285 books in the second week for a book donation drive. How many books were collected in all? To find out, we add the two numbers.
Sometimes when we add, the total in a column is more than 9. Then we carry the extra to the next column. This is called regrouping.
If the school gave away 268 books from a stock of 503, how many are left? We subtract. Sometimes the top digit is smaller, so we borrow from the next column.
Example: 347 + 285
| H | T | O | |
|---|---|---|---|
| 3 | 4 | 7 | |
| + | 2 | 8 | 5 |
| = | 6 | 3 | 2 |
Step 1 (Ones): 7 + 5 = 12. Write 2 in the Ones column. Carry 1 to the Tens column.
Step 2 (Tens): 4 + 8 = 12, plus the carried 1 = 13. Write 3 in the Tens column. Carry 1 to the Hundreds column.
Step 3 (Hundreds): 3 + 2 = 5, plus the carried 1 = 6. Write 6 in the Hundreds column.
Answer: 347 + 285 = 632
Example: 503 - 268
| H | T | O | |
|---|---|---|---|
| 5 | 0 | 3 | |
| − | 2 | 6 | 8 |
| = | 2 | 3 | 5 |
Step 1 (Ones): 3 − 8? We cannot! Borrow 1 ten from the Tens column. But Tens column is 0, so borrow 1 hundred from the Hundreds column first. H becomes 4, T becomes 10. Now borrow 1 ten for Ones: T becomes 9, O becomes 13. Now 13 − 8 = 5.
Step 2 (Tens): 9 − 6 = 3.
Step 3 (Hundreds): 4 − 2 = 2.
Answer: 503 − 268 = 235
Rule: Difference + Smaller Number = Bigger Number. If this is true, your subtraction is correct.
| Word | Meaning |
|---|---|
| Carrying (Regrouping) | When the sum in a column is 10 or more, we write the ones digit and carry the tens digit to the next column |
| Borrowing (Regrouping) | When the top digit is smaller, we take 1 from the next column to make it bigger |
| Sum | The answer we get after adding |
| Difference | The answer we get after subtracting |
| Place Value | The value of a digit based on its position (Ones, Tens, Hundreds) |
Number Detective: Solve each subtraction below. Then check your answer by adding the difference to the smaller number. Write "Correct" or "Try Again" next to each.
1. 704 − 389 = _________ Check: _________ + 389 = _________
2. 561 − 275 = _________ Check: _________ + 275 = _________
3. 830 − 462 = _________ Check: _________ + 462 = _________
Challenge: Write your own 3-digit addition sum where carrying happens in all three columns. Solve it and ask a friend to check!
My sum: _________ + _________ = _________
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Meena's school collected 347 books in the first week and 285 books in the second week for a book donation drive. How many books were collected in all? To find out, we add the two numbers.
Sometimes when we add, the total in a column is more than 9. Then we carry the extra to the next column. This is called regrouping.
If the school gave away 268 books from a stock of 503, how many are left? We subtract. Sometimes the top digit is smaller, so we borrow from the next column.
Example: 347 + 285
| H | T | O | |
|---|---|---|---|
| 3 | 4 | 7 | |
| + | 2 | 8 | 5 |
| = | 6 | 3 | 2 |
Step 1 (Ones): 7 + 5 = 12. Write 2 in the Ones column. Carry 1 to the Tens column.
Step 2 (Tens): 4 + 8 = 12, plus the carried 1 = 13. Write 3 in the Tens column. Carry 1 to the Hundreds column.
Step 3 (Hundreds): 3 + 2 = 5, plus the carried 1 = 6. Write 6 in the Hundreds column.
Answer: 347 + 285 = 632
Example: 503 - 268
| H | T | O | |
|---|---|---|---|
| 5 | 0 | 3 | |
| − | 2 | 6 | 8 |
| = | 2 | 3 | 5 |
Step 1 (Ones): 3 − 8? We cannot! Borrow 1 ten from the Tens column. But Tens column is 0, so borrow 1 hundred from the Hundreds column first. H becomes 4, T becomes 10. Now borrow 1 ten for Ones: T becomes 9, O becomes 13. Now 13 − 8 = 5.
Step 2 (Tens): 9 − 6 = 3.
Step 3 (Hundreds): 4 − 2 = 2.
Answer: 503 − 268 = 235
Think: If 503 − 268 = 235, then 235 + 268 should give us back 503. Let us check: 235 + 268 = 503. Correct!
Rule: Difference + Smaller Number = Bigger Number. If this is true, your subtraction is correct.
| Word | Meaning |
|---|---|
| Carrying (Regrouping) | When the sum in a column is 10 or more, we write the ones digit and carry the tens digit to the next column |
| Borrowing (Regrouping) | When the top digit is smaller, we take 1 from the next column to make it bigger |
| Sum | The answer we get after adding |
| Difference | The answer we get after subtracting |
| Place Value | The value of a digit based on its position (Ones, Tens, Hundreds) |
456 + 378: Ones: 6+8=14, write 4 carry 1. Tens: 5+7=12+1=13, write 3 carry 1. Hundreds: 4+3=7+1=8. Answer: 834.
700 − 356: Borrow step by step. O: 10−6=4, T: 9−5=4, H: 6−3=3. Answer: 344.
A. Addition (with carrying)
B. Subtraction (with borrowing)
Number Detective: Solve each subtraction below. Then check your answer by adding the difference to the smaller number. Write "Correct" or "Try Again" next to each.
1. 704 − 389 = _________ Check: _________ + 389 = _________
2. 561 − 275 = _________ Check: _________ + 275 = _________
3. 830 − 462 = _________ Check: _________ + 462 = _________
Challenge: Write your own 3-digit addition sum where carrying happens in all three columns. Solve it and ask a friend to check!
My sum: _________ + _________ = _________