Subtracting Three-Digit Numbers with Regrouping — Math Worksheet for 10-Year-Olds (Grade 4)

Instructions

Welcome, Subtraction Detective! Your mission is to solve these cases by using your subtraction skills. Pay close attention to regrouping (sometimes called 'borrowing') to crack each code and find the correct answer.

1. Read each section carefully. Start with the Warm-Up Case Files to get your mind ready.
2. For each problem, write your answer in the space provided. Show your work when possible.
3. Remember to check your answers. A good detective always double-checks the evidence!
4. Try the optional Detective's Challenge at the end if you're ready for a tougher case.

Section 1: Warm-Up Case Files

In these problems, you'll need to regroup from the tens place. We've solved the first one for you as an example.

Example:

  3  15
4  4  5

• 1 2 8

  3 1 7

Now, solve the following cases:

1. 572 - 239

   5  7  2

   • 2 3 9

2. 834 - 116

   8  3  4

   • 1 1 6

3. 690 - 457

   6  9  0

   • 4 5 7

4. 763 - 325

   7  6  3

   • 3 2 5

Section 2: Cracking the Code

These cases are trickier! You may need to regroup from the hundreds place or even across a zero.

1. 627 - 384

   6  2  7

   • 3 8 4

2. 915 - 539

   9  1  5

   • 5 3 9

3. 506 - 218

   5  0  6

   • 2 1 8

4. 800 - 471

   8  0  0

   • 4 7 1

Section 3: Word Problem Mysteries

Read each clue carefully to solve the mystery. Show your work.

1. The local library has 742 mystery novels. Last month, 258 of them were checked out. How many mystery novels were still on the shelf?

   Answer: __ novels

2. Detective Jones drove 525 miles to follow a lead. Her partner, Detective Smith, drove 389 miles. How many more miles did Detective Jones drive than Detective Smith?

   Answer: __ more miles

3. A baker made 600 cookies for the town festival. By the end of the day, he had sold 483. How many cookies were left over?

   Answer: __ cookies left over

Section 4: Detective's Challenge (Optional)

Case of the Faulty Calculation: Another detective tried to solve the problem below, but made a mistake. Your job is to find the error, explain what they did wrong, and solve the problem correctly.

The Faulty Calculation:

  7  2  3

• 4 9 8

  3 7 5

1. What was the mistake? (Hint: Look closely at the ones and tens columns.)

2. Solve the problem correctly in the space below.

  7  2  3

• 4 9 8

Answer Key

Section 1: Warm-Up Case Files

1. 572 - 239 = 333
2. 834 - 116 = 718
3. 690 - 457 = 233
4. 763 - 325 = 438

Section 2: Cracking the Code

1. 627 - 384 = 243
2. 915 - 539 = 376
3. 506 - 218 = 288
4. 800 - 471 = 329

Section 3: Word Problem Mysteries

1. 742 - 258 = 484 novels
2. 525 - 389 = 136 more miles
3. 600 - 483 = 117 cookies left over

Section 4: Detective's Challenge (Optional)

1. Mistake: The detective subtracted the smaller digit from the larger digit in the ones and tens columns instead of regrouping. They did 8-3 in the ones column and 9-2 in the tens column, which is incorrect.
2. Correct Answer: 723 - 498 = 225