➕ Addition and Subtraction
Class 4 Maths · Unit 2 of 12 · about 120 minutes
Builds on place value to add and subtract 4-digit numbers with regrouping. Children use column algorithms, estimate to check answers, find missing numbers in equations, and solve two-step word problems. This unit is essential for later units on multiplication, division, measurement, and money.
What your child will learn
- Students will be able to add two 4-digit numbers with regrouping using the column method.
- Students will be able to subtract a 4-digit number from another 4-digit number with regrouping using the column method.
- Students will be able to estimate the sum or difference of two 4-digit numbers by rounding to the nearest thousand or hundred, and use the estimate to check the reasonableness of an exact answer.
- Students will be able to find the missing number in addition and subtraction equations with 4-digit numbers.
- Students will be able to solve two-step word problems involving addition and subtraction of 4-digit numbers.
Lessons in this unit
- Adding 4-digit numbers with regrouping: Add two 4-digit numbers using the column method, regrouping from ones to thousands. Use base-10 blocks to show regrouping concretely, then move to the abstract algorithm.
- Subtracting 4-digit numbers with regrouping: Subtract a 4-digit number from another using the column method, regrouping across zeros. Use base-10 blocks to show regrouping concretely.
- Estimating to check answers: Round 4-digit numbers to the nearest thousand or hundred to estimate sums and differences, and use the estimate to check if an exact answer is reasonable.
- Finding missing numbers: Find the missing number in addition and subtraction equations with 4-digit numbers, using inverse operations.
- Two-step word problems: Solve word problems that require two operations (addition and/or subtraction) with 4-digit numbers. Use bar models to represent the problem.
Key words
- regroup
- To trade 10 ones for 1 ten, or 10 tens for 1 hundred, and so on.
- estimate
- To find a close answer without calculating exactly.
- missing number
- A number that is not shown in an equation, like ___ + 5 = 12.
- two-step problem
- A problem that needs two different calculations to solve.
- sum
- The answer you get when you add.
- difference
- The answer you get when you subtract.
Help your child at home
What to watch for
- When adding, start from the left (thousands) instead of the right (ones).
- Help: Always start from the ones column because regrouping affects the next column to the left.
- When subtracting, you can subtract the smaller digit from the larger digit in any column, regardless of which number is on top.
- Help: Always subtract the bottom digit from the top digit. If the top is smaller, regroup from the next column.
- Rounding to the nearest thousand means looking at the thousands digit only.
- Help: Look at the hundreds digit. If it is 5 or more, round up; if less than 5, round down.
- To find a missing addend, you add the known addend to the sum.
- Help: To find a missing addend, subtract the known addend from the sum.
Try this at home
- Add 3456 + 2789 in columns: 6 + 9 = 15, write 5 and carry 1 to the tens; repeat for each column
- Subtract 2789 from 3456 (regrouping in ones and tens)
- Estimate 3456 + 2789 by rounding to nearest thousand
- Find ___ in ___ + 4567 = 6000: the whole is 6000 and one part is 4567, so the missing part is 6000 - 4567 = 1433
Quick questions to ask aloud
- True or false: When adding 4-digit numbers, we always start from the ones column.
Show answer
True. Yes, we start from the ones column because regrouping affects the next column to the left. - Kabir has 4321 beads. He gives 1234 beads to his sister. How many beads does Kabir have left?
Show answer
4321 - 1234 = 3087. Subtract ones: 1-4, borrow from tens (2 becomes 1, ones become 11). 11-4=7. Tens: 1-3, borrow from hundreds (3 becomes 2, tens become 11). 11-3=8. Hundreds: 2-2=0. Thousands: 4-1=3. So the answer is 3087. - Estimate 3456 + 2789 by rounding each number to the nearest thousand. (6000 / 5000 / 7000 / 6500)
Show answer
3456 rounds to 3000 (hundreds digit 4 < 5). 2789 rounds to 3000 (hundreds digit 7 ≥ 5). So the estimate is 3000 + 3000 = 6000.
Frequently asked questions
What will my child learn in "Addition and Subtraction" (Class 4 Maths)?
Your child will be able to: add two 4-digit numbers with regrouping using the column method.; subtract a 4-digit number from another 4-digit number with regrouping using the column method.; estimate the sum or difference of two 4-digit numbers by rounding to the nearest thousand or hundred, and use the estimate to check the reasonableness of an exact answer.; find the missing number in addition and subtraction equations with 4-digit numbers.; solve two-step word problems involving addition and subtraction of 4-digit numbers..
How does MangoMindz teach "Addition and Subtraction"?
In 5 short parts (Adding 4-digit numbers with regrouping, Subtracting 4-digit numbers with regrouping, Estimating to check answers, Finding missing numbers, Two-step word problems). 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 "Addition and Subtraction" take?
About 120 minutes in total, spread over 5 parts of 15–25 minutes each.
How can I help my child with "Addition and Subtraction" at home?
Work through a small example together, such as: Add 3456 + 2789 in columns: 6 + 9 = 15, write 5 and carry 1 to the tens; repeat for each column; Subtract 2789 from 3456 (regrouping in ones and tens). Then ask a quick question aloud: True or false: When adding 4-digit numbers, we always start from the ones column.
What mistakes do children often make in "Addition and Subtraction"?
When adding, start from the left (thousands) instead of the right (ones). Fix: Always start from the ones column because regrouping affects the next column to the left. When subtracting, you can subtract the smaller digit from the larger digit in any column, regardless of which number is on top. Fix: Always subtract the bottom digit from the top digit. If the top is smaller, regroup from the next column. Rounding to the nearest thousand means looking at the thousands digit only. Fix: Look at the hundreds digit. If it is 5 or more, round up; if less than 5, round down.
Is "Addition and Subtraction" free on MangoMindz?
Yes. Every lesson part and quiz in "Addition and Subtraction" is free on MangoMindz, with no ads.