A three-digit number is made of hundreds, tens, and ones, so 256 is 200 and 50 and 6 put together.
In addition, when a column adds up to 10 or more you carry 1 to the next place, and in subtraction, when you cannot take away enough you borrow 10 from the place above.
When you handle big numbers, like saving your allowance or counting items, you line up the places and work through them step by step in a vertical calculation.
On this page you can choose addition or subtraction, change the two numbers, and watch the process with place-value blocks and the vertical form.
What is Place Value?
🧱 Numbers Have Places!
①Look at 256: 2 is hundreds, 5 is tens, 6 is ones
②2 in hundreds = 200, 5 in tens = 50, 6 in ones = 6
③Splitting digits into blocks makes addition/subtraction easy!
Calculation with Blocks
256
187
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Calculating by separating into place value blocks
💡 Carrying and Borrowing
①Addition: if ones sum ≥ 10, carry 1 to tens
②Subtraction: if cannot subtract in ones, borrow 10 from tens
③Step by step calculation makes big numbers easy!
Vertical Calculation
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Vertical calculation aligned by place value
✏️ Vertical Calculation Order
①Align by place value vertically
②Start from the ones place!
③Mark carry/borrow with small digits
④Continue tens, then hundreds — done!
Summary
Calculation Order
Ones → Tens → Hundreds
Align places and calculate from ones first
Carrying
Place sum ≥ 10 → carry 1 up
If ones sum ≥ 10, add 1 to tens
Borrowing
Subtractor bigger → borrow 10 from above
When you can't subtract, borrow 10 from the upper place
🎯 Key Points
①Always calculate from ones place
②Carry: if sum > 10, carry 1 up
③Borrow: if cannot subtract, borrow 10
④Align places when writing vertically
⑤Always check after calculating
Examples and Unit Test
Example 1
Calculate 256 + 187 using vertical addition.
1
Ones: 6 + 7 = 13. Write 3 and carry 1 to the tens.
2
Tens: 5 + 8 + 1(carry) = 14. Write 4, carry 1 to hundreds. Hundreds: 2 + 1 + 1 = 4. The answer is 443.
▸ 443
Carrying means moving 1 up when a column sum is 10 or more.
Example 2
Calculate 423 − 158 using vertical subtraction.
1
Ones: you cannot take 8 from 3. Borrow 10 from the tens: 13 − 8 = 5.
2
Tens: after lending it is 1; 1 − 5 cannot be done, so borrow from hundreds: 11 − 5 = 6. Hundreds: 4 − 1 − 1 = 2. The answer is 265.
▸ 265
Borrowing takes 10 from the upper place, which then decreases by 1.