Three-Digit Addition & Subtraction — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. A bakery made 534 muffins on Monday and 389 on Tuesday. They sold 476. How many muffins are left?
A) 437
B) 447
C) 457
D) 547
First add Monday and Tuesday: 534 + 389 = 923 muffins made in total. Then subtract the muffins sold: 923 - 476 = 447 muffins left.
2. What is the best estimate for 812 - 397 when both numbers are rounded to the nearest hundred?
A) 300
B) 400
C) 500
D) 600
Rounding to the nearest hundred makes 812 become 800 and 397 become 400. Subtracting the estimates, 800 - 400 = 400, which is the best estimate.
3. Ella reads 267 pages one week and 345 pages the next week. Her goal is 700 pages. How many more pages does she need?
A) 78
B) 88
C) 98
D) 108
Add the two weeks of reading: 267 + 345 = 612 pages. To reach the goal of 700, Ella still needs 700 - 612 = 88 more pages.
4. Which addition problem does NOT require regrouping in any place?
A) 456 + 378
B) 324 + 251
C) 189 + 467
D) 548 + 276
In 324 + 251, every column adds to less than 10: 4 + 1 = 5, 2 + 5 = 7, and 3 + 2 = 5. The other problems each have at least one column that sums to 10 or more, so they require regrouping.
Part B: Fill in the Blank
Write the correct answer on each line.
1. 256 + 478 + 139 = 873.
Add the first two numbers: 256 + 478 = 734. Then add the third: 734 + 139 = 873. Carrying happens in both steps as the column sums pass 10.
2. A zoo has 514 visitors on Saturday and 379 on Sunday. The total is 893.
Adding the two days of visitors gives the total: 514 + 379. The ones add to 13, the tens to 9, and the hundreds to 8 after the carry, making 893.
3. 900 - 563 = 337.
Because 900 has zeros in the tens and ones, you borrow across both columns to get 8-9-10 minus 5-6-3. That gives 337.
4. The difference between 742 and 385 is 357.
Subtracting the smaller from the larger gives the difference: 742 - 385. Borrowing is needed in the ones and tens, and the result is 357.
5. 1000 - 482 = 518.
Subtracting from 1000 requires borrowing across all the zeros, leaving 9-9-10 minus 4-8-2. That subtraction gives 518.