Three-Digit Addition and Subtraction — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. A bakery made 512 muffins on Monday and 389 on Tuesday. They sold 674 muffins by Wednesday. How many muffins are left?
A) 217
B) 227
C) 237
D) 327
First add the muffins baked: 512 + 389 = 901. Then subtract the muffins sold: 901 - 674 = 227 muffins left.
2. What is the best estimate for 748 + 153 when both numbers are rounded to the nearest hundred?
A) 800
B) 900
C) 1000
D) 1100
Round 748 to 700 and 153 to 200. Then 700 + 200 = 900, so the best estimate is 900.
3. Liam saved 463 coins. He spent 178 on a toy and 129 on a book. How many coins does he have left?
A) 146
B) 156
C) 166
D) 256
First add what Liam spent: 178 + 129 = 307 coins. Then subtract from his savings: 463 - 307 = 156 coins left.
4. Which subtraction problem requires borrowing across a zero?
A) 567 - 234
B) 803 - 457
C) 689 - 345
D) 756 - 321
In 803 - 457, the tens digit is 0, so you cannot borrow from it directly. You must first borrow from the hundreds to turn the 0 into 10, then borrow from there for the ones.
Part B: Fill in the Blank
Write the correct answer on each line.
1. 183 + 429 + 265 = 877.
Add the first two: 183 + 429 = 612. Then add the third: 612 + 265 = 877. Regroup in the ones each time.
2. A zoo has 756 visitors on Saturday. If 389 leave before lunch, 367 visitors remain.
Subtract 756 - 389: ones 6 < 9, borrow to get 16 - 9 = 7. Tens: 4 - 8 needs borrowing: 14 - 8 = 6. Hundreds: 6 - 3 = 3. So 367 visitors remain.
3. 900 - 463 = 437.
900 has zeros in the ones and tens, so borrow across both: 10 - 3 = 7, 9 - 6 = 3, 8 - 4 = 4. The difference is 437.
4. The sum of 374 and 458 is 832.
Add ones: 4 + 8 = 12, carry 1. Tens: 7 + 5 + 1 = 13, carry 1. Hundreds: 3 + 4 + 1 = 8. The sum of 374 and 458 is 832.
5. 1000 - 586 = 414.
To subtract from 1000, borrow across all three zeros: 10 - 6 = 4, 9 - 8 = 1, 9 - 5 = 4. The difference is 414.