➖ Subtraction up to 999
Class 3 Maths · Unit 3 of 12 · about 170 minutes
Subtracts two- and three-digit numbers within 999, first without regrouping and then by breaking a ten or a hundred (borrowing), including numbers with zeros. Children check by adding back, subtract mentally with friendly strategies, estimate, and solve take-away and comparison word problems.
What your child will learn
- Students will be able to subtract three-digit numbers without regrouping using blocks and the column method.
- Students will be able to subtract by breaking one ten into ten ones when the ones digit is too small.
- Students will be able to subtract by breaking a hundred into ten tens, including borrowing in both columns and from numbers with zeros.
- Students will be able to check a subtraction by adding the answer to the number taken away.
- Students will be able to subtract mentally using counting up, taking away tens and hundreds, and near numbers, and estimate a difference by rounding.
- Students will be able to solve take-away, missing-part and comparison word problems, choosing subtraction from the meaning of the story.
Lessons in this unit
- Taking away without borrowing: Subtract in columns when every top digit is big enough, using blocks removed from a pile and then the column method.
- Breaking a ten: When the ones digit on top is too small, open one ten into ten ones with blocks, then record it: the tens digit goes down by 1 and the ones digit gains 10.
- Breaking a hundred: Borrow from the hundreds when the tens are too small, including problems that borrow in both columns and top numbers with zeros (e.g. 500 − 237, 604 − 358).
- Subtracting in your head and estimating: Subtract without columns by counting up from the smaller number, taking away hundreds and tens, and using near numbers; then estimate a difference by rounding to the nearest ten.
- Story sums with subtraction: Solve three kinds of subtraction stories: take away (left), missing part (how many more are needed) and comparison (how many more / fewer). Use a bar model to decide, then solve and check.
Key words
- difference
- The answer when we subtract; how far apart two numbers are.
- borrow / break a ten
- Open one ten into 10 ones (or one hundred into 10 tens) so we have enough to take away.
- take away
- Remove some from a group.
- how many more / fewer
- Compare two groups by finding the difference.
- left / remaining
- What stays after some is taken away.
Help your child at home
What to watch for
- Always subtract the smaller digit from the bigger one, whichever row it is in.
- Help: The top number is the whole. We always take the bottom digit away from the top digit. If the top is too small, we borrow (next lesson).
- 2 − 7 is 'not possible' so do 7 − 2 = 5: 452 − 127 = 335.
- Help: The top number is the whole. Open a ten: 12 − 7 = 5, and the tens become 4. The answer is 325.
- 0 − 7 = 7 (or 0): zeros are treated as 'nothing to do'.
- Help: 0 ones cannot give 7. Borrow: but the tens are 0 too, so first break a hundred into 10 tens, then one ten into 10 ones.
- 645 − 199 = 445 (take 200, then take 1 more).
- Help: 199 is 1 less than 200. We took away 1 too many, so give 1 back: 445 + 1 = 446.
Try this at home
- 578 − 234 with blocks and columns
- 452 − 127 with block exchange, then columns
- 528 − 364 with hundred exchange
- 300 − 198 by counting up: 198 → 200 → 300
Quick questions to ask aloud
- Subtract: 578 − 234
Show answer
Ones: 8 − 4 = 4. Tens: 7 − 3 = 4. Hundreds: 5 − 2 = 3. The difference is 344. - Subtract: 452 − 127
Show answer
Ones: 2 is smaller than 7, so open a ten. 12 − 7 = 5. Tens: 4 − 2 = 2. Hundreds: 4 − 1 = 3. The answer is 325. - Subtract: 528 − 364
Show answer
Ones: 8 − 4 = 4. Tens: 2 is smaller than 6, so open a hundred: 12 tens − 6 tens = 6 tens, and hundreds become 4. Hundreds: 4 − 3 = 1. The answer is 164.
Frequently asked questions
What will my child learn in "Subtraction up to 999" (Class 3 Maths)?
Your child will be able to: subtract three-digit numbers without regrouping using blocks and the column method.; subtract by breaking one ten into ten ones when the ones digit is too small.; subtract by breaking a hundred into ten tens, including borrowing in both columns and from numbers with zeros.; check a subtraction by adding the answer to the number taken away.; subtract mentally using counting up, taking away tens and hundreds, and near numbers, and estimate a difference by rounding.; solve take-away, missing-part and comparison word problems, choosing subtraction from the meaning of the story..
How does MangoMindz teach "Subtraction up to 999"?
In 5 short parts (Taking away without borrowing, Breaking a ten, Breaking a hundred, Subtracting in your head and estimating, Story sums with subtraction). Each part has a picture-based lesson read aloud by Mango Teacher, a quick check, and a quiz built from common mistakes children make, with Mango, a study buddy, for questions.
How long does "Subtraction up to 999" take?
About 170 minutes in total, spread over 5 parts of 15–25 minutes each.
How can I help my child with "Subtraction up to 999" at home?
Work through a small example together, such as: 578 − 234 with blocks and columns; 452 − 127 with block exchange, then columns. Then ask a quick question aloud: Subtract: 578 − 234
What mistakes do children often make in "Subtraction up to 999"?
Always subtract the smaller digit from the bigger one, whichever row it is in. Fix: The top number is the whole. We always take the bottom digit away from the top digit. If the top is too small, we borrow (next lesson). 2 − 7 is 'not possible' so do 7 − 2 = 5: 452 − 127 = 335. Fix: The top number is the whole. Open a ten: 12 − 7 = 5, and the tens become 4. The answer is 325. 0 − 7 = 7 (or 0): zeros are treated as 'nothing to do'. Fix: 0 ones cannot give 7. Borrow: but the tens are 0 too, so first break a hundred into 10 tens, then one ten into 10 ones.
Is "Subtraction up to 999" free on MangoMindz?
Yes. Every lesson part and quiz in "Subtraction up to 999" is free on MangoMindz, with no ads.