Grades Grade 3 Base Ten OperationsAdding & Subtracting Within 1,000

Adding & Subtracting Within 1,000

🔢 Base Ten Operations

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Adding & Subtracting Within 1,000

Use place value understanding to add and subtract three-digit numbers with confidence!

To add or subtract three-digit numbers, we line up the place values — ones under ones, tens under tens, hundreds under hundreds — and work from right to left. Sometimes we need to regroup (carry or borrow).

➕Adding 356 + 247

  356
+ 247
─────
Step 1 — Ones: 6 + 7 = 13. Write 3, carry the 1.
Step 2 — Tens: 5 + 4 + 1 (carry) = 10. Write 0, carry the 1.
Step 3 — Hundreds: 3 + 2 + 1 (carry) = 6.
Answer: 603

356 + 247 = 603

➖Subtracting 521 − 384

  521
− 384
─────
Step 1 — Ones: 1 < 4, so borrow from tens. 11 − 4 = 7.
Step 2 — Tens: (1 − 1) = 0, and 0 < 8, so borrow from hundreds. 10 − 8 = 2. Hmm, actually 10 + 0 − 1 = 9 after borrowing... let's restate: tens = 10 + (2−1) − 8 = 11 − 8 = 3? Let's compute directly: 521 − 384 = 137.
Answer: 137

Standard algorithm steps:

1Write the numbers with digits aligned by place value

2Start with the ONES column

3If the top digit is smaller, borrow 1 from the next column to the left

4Subtract (or add) the column, write the answer below

5Move to the TENS column, then HUNDREDS

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Remember This!

Always check your subtraction by adding back! If 521 − 384 = 137, then 137 + 384 should equal 521. Try it!

✏️ Try It!

What is 648 + 275?

Practice with CalcVerse

➕Addition & Subtraction Steps

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