Addition & Subtraction – Grade 4 Maths

Mental Addition

Number bonds and bridging through 100

Column Addition

Adding 4-digit numbers with carrying

Mental Subtraction

Counting on and complementary methods

Column Subtraction

Subtracting with exchange (borrowing)

Estimation

Round first, then check your answer

1. Mental Addition

Use number bonds and bridging to add mentally.

Number bonds to 100:
47 + 53 = 100 | 38 + 62 = 100 | 75 + 25 = 100

Bridging through 100:
85 + 37 = 85 + 15 + 22 = 100 + 22 = 122
(Split 37 into 15 + 22 to reach 100 first)

💡 Look for pairs that make 10 or 100. These are "friendly" numbers that make mental maths much quicker!

2. Column Addition (up to 4 digits)

Line up digits by place value. Add from right to left. Carry when a column totals 10 or more.

        With carrying:  1 8 7 6 + 2 4 5 6

        Ones: 6+6=12 → write 2, carry 1

        Tens: 7+5+1=13 → write 3, carry 1

        Hundreds: 8+4+1=13 → write 3, carry 1

        Thousands: 1+2+1=4

        Answer: 4,332

3. Mental Subtraction

Two useful strategies: counting on and complementary subtraction.

Counting on (find the difference):
100 − 52: start at 52, count on to 100.
52 → 60 (+8) → 100 (+40) → total = 48

Complementary subtraction:
1,000 − 600 = 400
(What do I add to 600 to get 1,000? Add 400)

💡 For numbers near a round number, use bridging: 300 − 148 = 300 − 150 + 2 = 152

4. Column Subtraction with Exchange

When a digit is too small to subtract from, exchange (borrow) from the next column.

        5,678 − 3,567:

          5 6 7 8

        − 3 5 6 7

        ─────────

          2 1 1 1

Exchange example: 4,302 − 1,456
Ones: can't do 2−6. Exchange from tens (but tens=0!).
Exchange from hundreds → 9 tens 12 ones.
12−6=6, 9−5=4... work through carefully column by column.

💡 Always check your answer by adding: answer + smaller number should equal the larger number.

5. Estimation and Checking

Before calculating, estimate by rounding each number to the nearest 100. This tells you roughly what to expect.

Estimate → Calculate → Check

2,345 + 1,876:
Estimate: 2,300 + 1,900 = 4,200
Exact: 2,345 + 1,876 = 4,221
4,221 is close to 4,200 ✓

💡 If your answer is very different from your estimate, you probably made an error — go back and check!

Example 1 — Mental Addition (bridging)

47 + 53 = ?

47 + 53: these are number bonds to 100.

Answer: 100

Example 2 — Column Addition

2,345 + 3,333 = ?

Ones: 5+3=8 Tens: 4+3=7 Hundreds: 3+3=6 Thousands: 2+3=5

Answer: 5,678

Example 3 — Mental Subtraction

100 − 52 = ?

Count on from 52: 52 → 60 (+8) → 100 (+40)

Answer: 48

Example 4 — Column Subtraction

5,678 − 3,567 = ?

Ones: 8−7=1 Tens: 7−6=1 Hundreds: 6−5=1 Thousands: 5−3=2

Answer: 2,111

Example 5 — Estimation

Estimate 3,456 + 4,123.

Round: 3,500 + 4,100 = 7,600 (estimate)

Exact: 3,456 + 4,123 = 7,579 (close to 7,600 ✓)

➕ Column Addition Solver

First number: Second number:

➖ Column Subtraction Solver

First number: Second number:

🎯 Estimation Check

Number A: Operation: Number B:

Exercise 1 — Mental Addition

1. 47 + 53 = ?

2. 600 + 400 = ?

3. 180 + 120 = ?

4. 250 + 250 = ?

5. 50 + 49 = ?

6. 130 + 70 = ?

7. 85 + 65 = ?

8. 38 + 37 = ?

9. 74 + 74 = ?

10. 125 + 125 = ?

Exercise 2 — Column Addition (4-digit)

1. 2,345 + 3,333 = ?

2. 3,456 + 4,434 = ?

3. 4,567 + 5,432 = ?

4. 4,321 + 4,444 = ?

5. 3,210 + 3,333 = ?

6. 5,678 + 4,123 = ?

7. 3,456 + 4,198 = ?

8. 4,500 + 4,401 = ?

9. 4,321 + 5,555 = ?

10. 2,345 + 3,087 = ?

Exercise 3 — Mental Subtraction

1. 100 − 50 = ?

2. 700 − 400 = ?

3. 500 − 300 = ?

4. 1,000 − 600 = ?

5. 75 − 50 = ?

6. 300 − 150 = ?

7. 125 − 50 = ?

8. 100 − 52 = ?

9. 1,000 − 500 = ?

10. 900 − 250 = ?

Exercise 4 — Column Subtraction

1. 5,678 − 3,567 = ?

2. 4,567 − 3,333 = ?

3. 7,890 − 4,434 = ?

4. 8,765 − 4,198 = ?

5. 6,543 − 4,198 = ?

6. 3,456 − 2,222 = ?

7. 9,876 − 4,198 = ?

8. 7,654 − 4,444 = ?

9. 8,765 − 4,444 = ?

10. 5,555 − 4,444 = ?

Exercise 5 — Word Problems

1. A school has 2,345 books. 1,234 are fiction. How many are non-fiction?

2. Town A has 4,567 people. Town B has 3,210. How many people altogether?

3. 1,234 − 567 + 345 = ?

4. 3,456 + 4,123 = ?

5. A train has 5,000 seats. 1,234 are taken. How many are free?

6. A shop earns £1,200 each month. How much in 3 months? (1200 × 3)

7. 5,000 − 2,456 = ?

8. 1,250 + 875 + 430 = ?

9. A coach holds 45 people. 1,250 people need transport. How many full coaches are needed? (Round up)

10. 8,500 − 3,276 = ?

🏋️ Practice — 20 Questions

1. 47 + 53 = ?

2. 600 + 400 = ?

3. 180 + 120 = ?

4. 250 + 250 = ?

5. 2,345 + 3,333 = ?

6. 3,456 + 4,434 = ?

7. 4,567 + 5,432 = ?

8. 100 − 50 = ?

9. 700 − 400 = ?

10. 5,678 − 3,567 = ?

11. 4,567 − 3,333 = ?

12. 7,890 − 4,434 = ?

13. 5,678 − 3,567 = ?

14. 4,567 + 3,210 = ?

15. 5,000 − 1,234 = ?

16. 5,000 − 2,456 = ?

17. 8,500 − 3,276 = ? (Hint: borrow carefully)

18. 100 − 52 = ?

19. 300 − 150 = ?

20. 125 − 50 = ?

🏆 Challenge — 8 Questions

1. 4,321 + 4,444 = ?

2. 8,765 − 6,420 = ?

3. 3,210 + 3,333 = ?

4. 9,876 − 6,420 = ?

5. 4,567 + 3,210 = ?

6. 5,000 − 1,234 = ?

7. 8,500 − 3,276 = ?

8. 5,555 − 4,444 = ?

➕ Addition & Subtraction