Lesson 9.1: Multi-Digit Addition with Regrouping (Carrying) and Estimation
Add 3- and 4-digit numbers with column alignment and regrouping, and check reasonableness using rounding estimation.
⏱️ Reading Time: 15 mins
• ❓ 50 Interactive Practice Questions
🌟
Real-Life Story: Addition and Subtraction
A school auditorium hosts two charity concerts. On Friday night, 1,485 attendees arrive; on Saturday, 1,738 attendees enter. The ticketing manager adds them column by column with regrouping: 1,485 + 1,738 = 3,223 total ticket holders.
💡 Core Mathematical Concepts: Multi-Digit Addition & Estimation
Focus areas: Addition with regrouping, column addition, sum, addends, estimation by rounding.
| Concept / Term | Mathematical Definition | Everyday Example |
|---|---|---|
| Column Addition Rule | Align digits strictly by place value (ones under ones, tens under tens, hundreds under hundreds) | Start adding from the ones column on the right |
| Regrouping (Carrying) | When a column sum is 10 or greater, write the ones digit in the answer and carry the tens digit to the next column | 7 + 8 = 15 (write 5, carry 1 ten) |
| Rounding Estimation | Round addends to the nearest hundred or thousand to quickly check answer reasonableness | 1,485 ≈ 1,500; 1,738 ≈ 1,700. Estimated sum ≈ 3,200 |
| Commutative Property | Changing the order of addends does not change the sum (a + b = b + a) | 350 + 620 = 620 + 350 = 970 |
🔍 Practical Classroom & Everyday Examples
Example 1: Checking Carried Digits
Always circle or clearly write the carried digit at the top of the next column so it is not forgotten during addition.
Example 2: Front-End Estimation
Sum the highest place values for a quick lower bound: 1,000 + 1,000 = 2,000.
⚠️ Watch Out! Common Mistakes to Avoid
Common Error: Misaligning digits of different lengths
Correction: Adding 2,450 + 85 with 8 under the thousands column instead of tens column!
Common Error: Forgetting the carried digit
Correction: Adding 700 + 800 and writing 1,500 without adding the 1 carried from the tens column.
🎯 Quick Self-Check Challenge
Calculate 2,674 + 1,589. First estimate by rounding to the nearest hundred, then compute the exact sum.
Answer & Explanation:
Estimate: 2,700 + 1,600 = 4,300. Exact: 4+9=13 (carry 1); 1+7+8=16 (carry 1); 1+6+5=12 (carry 1); 1+2+1=4. Exact sum = 4,263.
🎯 Key Learning Takeaways
Master Addition and Subtraction fundamentals.
📄 Printable Worksheets (5 Available)
Download ready-to-print PDFs for offline student practice with separate parent/teacher answer keys.
G3-M-CH09-WS05
A4 • 15 Qs
Addition and Subtraction — Worksheet 5
Regrouping, Estimation & Multi-Digit Operations (Wildlife Sanctuary Visitor Registry)
G3-M-CH09-WS04
A4 • 15 Qs
Addition and Subtraction — Worksheet 4
Regrouping, Estimation & Multi-Digit Operations (Public Library Book Circulation)
G3-M-CH09-WS03
A4 • 15 Qs
Addition and Subtraction — Worksheet 3
Regrouping, Estimation & Multi-Digit Operations (City Botanical Seed Distribution)
G3-M-CH09-WS02
A4 • 15 Qs
Addition and Subtraction — Worksheet 2
Regrouping, Estimation & Multi-Digit Operations (School Sports Equipment Warehouse)
G3-M-CH09-WS01
A4 • 15 Qs
Addition and Subtraction — Worksheet 1
Regrouping, Estimation & Multi-Digit Operations (Community Food Bank Drive)
✍️ Lesson Practice Questions (50 Questions)
Solve these real-world challenges online, test your understanding, and reveal instant step-by-step explanations.
1
Short Answer
Hard
2 Marks
The sum of two 4-digit numbers is 8,240. If one number is 1,500 greater than the other, what is the smaller number?
A
3,370
B
3,470
C
4,870
D
3,270
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
3,370
Step-by-Step Explanation:
Subtract the difference first: 8,240 - 1,500 = 6,740. Divide equally between the two: 6,740 ÷ 2 = 3,370.
2
Short Answer
Hard
2 Marks
A charity fundraiser aimed to collect $7,500. On Monday they raised $2,840, on Tuesday $1,950, and on Wednesday $1,630. How much more money is needed to reach the goal?
A
$1,080
B
$1,180
C
$980
D
$1,280
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
$1,080
Step-by-Step Explanation:
Total raised = 2,840 + 1,950 + 1,630 = 6,420. Remaining needed = 7,500 - 6,420 = $1,080.
3
Short Answer
Hard
2 Marks
If the sum of two numbers is 5,000 and one number is 2,750, how can you find the other number?
A
Subtract 2,750 from 5,000 (5,000 - 2,750 = 2,250)
B
Add 5,000 + 2,750
C
Multiply 5,000 × 2,750
D
Divide 5,000 by 2
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Subtract 2,750 from 5,000 (5,000 - 2,750 = 2,250)
Step-by-Step Explanation:
Subtraction is the inverse of addition: Sum - Known Addend = Unknown Addend.
4
Short Answer
Hard
2 Marks
Why does subtracting 1 from both numbers in a problem like 5,000 - 2,347 (giving 4,999 - 2,346) produce the exact same correct answer without any borrowing?
A
Because shifting both numbers by the same amount preserves the exact difference between them, while 4,999 requires no borrowing across zeroes
B
Because 4,999 is an easy number to write
C
Because zeroes disappear in math
D
It only works on leap years
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Because shifting both numbers by the same amount preserves the exact difference between them, while 4,999 requires no borrowing across zeroes
Step-by-Step Explanation:
The difference between two values (a - b) remains identical if both values shift by the same constant: (a - 1) - (b - 1) = a - b.
5
Short Answer
Medium
1 Mark
Maya solves 2,400 - 1,150 = 1,350 and checks her work by adding 1,350 + 2,400 = 3,750. What is wrong with Maya's checking method?
A
To check subtraction, add the DIFFERENCE to the SUBTRAHEND (1,350 + 1,150 = 2,400), not to the minuend
B
Maya should check by dividing
C
Subtraction cannot be checked
D
Maya's subtraction was wrong
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
To check subtraction, add the DIFFERENCE to the SUBTRAHEND (1,350 + 1,150 = 2,400), not to the minuend
Step-by-Step Explanation:
Difference + Subtrahend = Minuend.
6
Short Answer
Medium
1 Mark
A student subtracts 62 - 28 and writes 46 because 8 - 2 = 6 and 6 - 2 = 4. What is the student's mistake?
A
The student subtracted the top digit from the bottom digit (8 - 2) instead of borrowing 10 from the tens place (12 - 8 = 4)
B
The student added instead of subtracting
C
62 cannot be subtracted by 28
D
The answer should be 44
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
The student subtracted the top digit from the bottom digit (8 - 2) instead of borrowing 10 from the tens place (12 - 8 = 4)
Step-by-Step Explanation:
Always subtract bottom from top; when top is smaller, borrow from the tens column (12 - 8 = 4, 5 - 2 = 3 → 34).
7
Fill in the Blanks
Medium
1 Mark
Find the missing digit: 3,4[ ? ]5 + 1,234 = 4,709
A
7
B
6
C
8
D
5
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
7
Step-by-Step Explanation:
Units: 5 + 4 = 9. Tens: [?] + 3 = 10 (0 with carry 1), so [?] = 7.
8
Fill in the Blanks
Medium
1 Mark
Find the missing addend: 5200 + [ ? ] = 8040
A
2840
B
2830
C
2860
D
2940
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2840
Step-by-Step Explanation:
Subtract known addend from sum: 8040 - 5200 = 2840.
9
Short Answer
Medium
1 Mark
A school library has 4,500 books. Students borrow 1,820 fiction books and 940 science books. How many total books were borrowed?
A
2,760 books
B
2,660 books
C
2,860 books
D
2,740 books
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2,760 books
Step-by-Step Explanation:
1,820 + 940 = 2,760 books borrowed.
10
Short Answer
Medium
1 Mark
A warehouse had 5200 boxes in stock. If 2840 boxes were dispatched for delivery, how many boxes remain in the warehouse?
A
2360 boxes
B
2380 boxes
C
2345 boxes
D
2410 boxes
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2360 boxes
Step-by-Step Explanation:
5200 - 2840 = 2360 boxes remain.
11
Short Answer
Medium
1 Mark
At the Wildlife Sanctuary Visitor Registry, staff collected 5200 items in Week 1 and 2840 items in Week 2. How many items were collected in total?
A
8040 items
B
7990 items
C
8140 items
D
8020 items
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
8040 items
Step-by-Step Explanation:
5200 + 2840 = 8040 items.
12
Multiple Choice
Easy
1 Mark
Evaluate: 4,000 - 1,250 =
A
2,750
B
2,850
C
3,750
D
2,650
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2,750
Step-by-Step Explanation:
4,000 - 1,250 = 2,750.
13
Multiple Choice
Easy
1 Mark
Estimate 3,890 + 2,120 by rounding each number to the nearest hundred:
A
6,000
B
5,900
C
6,100
D
5,800
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
6,000
Step-by-Step Explanation:
3,890 rounds to 3,900. 2,120 rounds to 2,100. 3,900 + 2,100 = 6,000.
14
Multiple Choice
Easy
1 Mark
Calculate: 5200 - 2840 =
A
2360
B
2370
C
2350
D
2460
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2360
Step-by-Step Explanation:
Subtract with regrouping: 5200 - 2840 = 2360.
15
Multiple Choice
Easy
1 Mark
Calculate: 5200 + 2840 =
A
8040
B
8030
C
8060
D
7940
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
8040
Step-by-Step Explanation:
Add with regrouping: 5200 + 2840 = 8040.
16
Short Answer
Hard
2 Marks
The sum of two 4-digit numbers is 8,240. If one number is 1,500 greater than the other, what is the smaller number?
A
3,370
B
3,470
C
4,870
D
3,270
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
3,370
Step-by-Step Explanation:
Subtract the difference first: 8,240 - 1,500 = 6,740. Divide equally between the two: 6,740 ÷ 2 = 3,370.
17
Short Answer
Hard
2 Marks
A charity fundraiser aimed to collect $7,500. On Monday they raised $2,840, on Tuesday $1,950, and on Wednesday $1,630. How much more money is needed to reach the goal?
A
$1,080
B
$1,180
C
$980
D
$1,280
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
$1,080
Step-by-Step Explanation:
Total raised = 2,840 + 1,950 + 1,630 = 6,420. Remaining needed = 7,500 - 6,420 = $1,080.
18
Short Answer
Hard
2 Marks
If the sum of two numbers is 5,000 and one number is 2,750, how can you find the other number?
A
Subtract 2,750 from 5,000 (5,000 - 2,750 = 2,250)
B
Add 5,000 + 2,750
C
Multiply 5,000 × 2,750
D
Divide 5,000 by 2
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Subtract 2,750 from 5,000 (5,000 - 2,750 = 2,250)
Step-by-Step Explanation:
Subtraction is the inverse of addition: Sum - Known Addend = Unknown Addend.
19
Short Answer
Hard
2 Marks
Why does subtracting 1 from both numbers in a problem like 5,000 - 2,347 (giving 4,999 - 2,346) produce the exact same correct answer without any borrowing?
A
Because shifting both numbers by the same amount preserves the exact difference between them, while 4,999 requires no borrowing across zeroes
B
Because 4,999 is an easy number to write
C
Because zeroes disappear in math
D
It only works on leap years
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Because shifting both numbers by the same amount preserves the exact difference between them, while 4,999 requires no borrowing across zeroes
Step-by-Step Explanation:
The difference between two values (a - b) remains identical if both values shift by the same constant: (a - 1) - (b - 1) = a - b.
20
Short Answer
Medium
1 Mark
Maya solves 2,400 - 1,150 = 1,350 and checks her work by adding 1,350 + 2,400 = 3,750. What is wrong with Maya's checking method?
A
To check subtraction, add the DIFFERENCE to the SUBTRAHEND (1,350 + 1,150 = 2,400), not to the minuend
B
Maya should check by dividing
C
Subtraction cannot be checked
D
Maya's subtraction was wrong
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
To check subtraction, add the DIFFERENCE to the SUBTRAHEND (1,350 + 1,150 = 2,400), not to the minuend
Step-by-Step Explanation:
Difference + Subtrahend = Minuend.
21
Short Answer
Medium
1 Mark
A student subtracts 62 - 28 and writes 46 because 8 - 2 = 6 and 6 - 2 = 4. What is the student's mistake?
A
The student subtracted the top digit from the bottom digit (8 - 2) instead of borrowing 10 from the tens place (12 - 8 = 4)
B
The student added instead of subtracting
C
62 cannot be subtracted by 28
D
The answer should be 44
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
The student subtracted the top digit from the bottom digit (8 - 2) instead of borrowing 10 from the tens place (12 - 8 = 4)
Step-by-Step Explanation:
Always subtract bottom from top; when top is smaller, borrow from the tens column (12 - 8 = 4, 5 - 2 = 3 → 34).
22
Fill in the Blanks
Medium
1 Mark
Find the missing digit: 3,4[ ? ]5 + 1,234 = 4,709
A
7
B
6
C
8
D
5
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
7
Step-by-Step Explanation:
Units: 5 + 4 = 9. Tens: [?] + 3 = 10 (0 with carry 1), so [?] = 7.
23
Fill in the Blanks
Medium
1 Mark
Find the missing addend: 3840 + [ ? ] = 5805
A
1965
B
1955
C
1985
D
2065
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
1965
Step-by-Step Explanation:
Subtract known addend from sum: 5805 - 3840 = 1965.
24
Short Answer
Medium
1 Mark
A school library has 4,500 books. Students borrow 1,820 fiction books and 940 science books. How many total books were borrowed?
A
2,760 books
B
2,660 books
C
2,860 books
D
2,740 books
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2,760 books
Step-by-Step Explanation:
1,820 + 940 = 2,760 books borrowed.
25
Short Answer
Medium
1 Mark
A warehouse had 3840 boxes in stock. If 1965 boxes were dispatched for delivery, how many boxes remain in the warehouse?
A
1875 boxes
B
1895 boxes
C
1860 boxes
D
1925 boxes
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
1875 boxes
Step-by-Step Explanation:
3840 - 1965 = 1875 boxes remain.
26
Short Answer
Medium
1 Mark
At the Public Library Book Circulation, staff collected 3840 items in Week 1 and 1965 items in Week 2. How many items were collected in total?
A
5805 items
B
5755 items
C
5905 items
D
5785 items
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
5805 items
Step-by-Step Explanation:
3840 + 1965 = 5805 items.
27
Multiple Choice
Easy
1 Mark
Evaluate: 4,000 - 1,250 =
A
2,750
B
2,850
C
3,750
D
2,650
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2,750
Step-by-Step Explanation:
4,000 - 1,250 = 2,750.
28
Multiple Choice
Easy
1 Mark
Estimate 3,890 + 2,120 by rounding each number to the nearest hundred:
A
6,000
B
5,900
C
6,100
D
5,800
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
6,000
Step-by-Step Explanation:
3,890 rounds to 3,900. 2,120 rounds to 2,100. 3,900 + 2,100 = 6,000.
29
Multiple Choice
Easy
1 Mark
Calculate: 3840 - 1965 =
A
1875
B
1885
C
1865
D
1975
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
1875
Step-by-Step Explanation:
Subtract with regrouping: 3840 - 1965 = 1875.
30
Multiple Choice
Easy
1 Mark
Calculate: 3840 + 1965 =
A
5805
B
5795
C
5825
D
5705
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
5805
Step-by-Step Explanation:
Add with regrouping: 3840 + 1965 = 5805.
31
Short Answer
Hard
2 Marks
The sum of two 4-digit numbers is 8,240. If one number is 1,500 greater than the other, what is the smaller number?
A
3,370
B
3,470
C
4,870
D
3,270
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
3,370
Step-by-Step Explanation:
Subtract the difference first: 8,240 - 1,500 = 6,740. Divide equally between the two: 6,740 ÷ 2 = 3,370.
32
Short Answer
Hard
2 Marks
A charity fundraiser aimed to collect $7,500. On Monday they raised $2,840, on Tuesday $1,950, and on Wednesday $1,630. How much more money is needed to reach the goal?
A
$1,080
B
$1,180
C
$980
D
$1,280
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
$1,080
Step-by-Step Explanation:
Total raised = 2,840 + 1,950 + 1,630 = 6,420. Remaining needed = 7,500 - 6,420 = $1,080.
33
Short Answer
Hard
2 Marks
If the sum of two numbers is 5,000 and one number is 2,750, how can you find the other number?
A
Subtract 2,750 from 5,000 (5,000 - 2,750 = 2,250)
B
Add 5,000 + 2,750
C
Multiply 5,000 × 2,750
D
Divide 5,000 by 2
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Subtract 2,750 from 5,000 (5,000 - 2,750 = 2,250)
Step-by-Step Explanation:
Subtraction is the inverse of addition: Sum - Known Addend = Unknown Addend.
34
Short Answer
Hard
2 Marks
Why does subtracting 1 from both numbers in a problem like 5,000 - 2,347 (giving 4,999 - 2,346) produce the exact same correct answer without any borrowing?
A
Because shifting both numbers by the same amount preserves the exact difference between them, while 4,999 requires no borrowing across zeroes
B
Because 4,999 is an easy number to write
C
Because zeroes disappear in math
D
It only works on leap years
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Because shifting both numbers by the same amount preserves the exact difference between them, while 4,999 requires no borrowing across zeroes
Step-by-Step Explanation:
The difference between two values (a - b) remains identical if both values shift by the same constant: (a - 1) - (b - 1) = a - b.
35
Short Answer
Medium
1 Mark
Maya solves 2,400 - 1,150 = 1,350 and checks her work by adding 1,350 + 2,400 = 3,750. What is wrong with Maya's checking method?
A
To check subtraction, add the DIFFERENCE to the SUBTRAHEND (1,350 + 1,150 = 2,400), not to the minuend
B
Maya should check by dividing
C
Subtraction cannot be checked
D
Maya's subtraction was wrong
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
To check subtraction, add the DIFFERENCE to the SUBTRAHEND (1,350 + 1,150 = 2,400), not to the minuend
Step-by-Step Explanation:
Difference + Subtrahend = Minuend.
36
Short Answer
Medium
1 Mark
A student subtracts 62 - 28 and writes 46 because 8 - 2 = 6 and 6 - 2 = 4. What is the student's mistake?
A
The student subtracted the top digit from the bottom digit (8 - 2) instead of borrowing 10 from the tens place (12 - 8 = 4)
B
The student added instead of subtracting
C
62 cannot be subtracted by 28
D
The answer should be 44
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
The student subtracted the top digit from the bottom digit (8 - 2) instead of borrowing 10 from the tens place (12 - 8 = 4)
Step-by-Step Explanation:
Always subtract bottom from top; when top is smaller, borrow from the tens column (12 - 8 = 4, 5 - 2 = 3 → 34).
37
Fill in the Blanks
Medium
1 Mark
Find the missing digit: 3,4[ ? ]5 + 1,234 = 4,709
A
7
B
6
C
8
D
5
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
7
Step-by-Step Explanation:
Units: 5 + 4 = 9. Tens: [?] + 3 = 10 (0 with carry 1), so [?] = 7.
38
Fill in the Blanks
Medium
1 Mark
Find the missing addend: 4500 + [ ? ] = 6775
A
2275
B
2265
C
2295
D
2375
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2275
Step-by-Step Explanation:
Subtract known addend from sum: 6775 - 4500 = 2275.
39
Short Answer
Medium
1 Mark
A school library has 4,500 books. Students borrow 1,820 fiction books and 940 science books. How many total books were borrowed?
A
2,760 books
B
2,660 books
C
2,860 books
D
2,740 books
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2,760 books
Step-by-Step Explanation:
1,820 + 940 = 2,760 books borrowed.
40
Short Answer
Medium
1 Mark
A warehouse had 4500 boxes in stock. If 2275 boxes were dispatched for delivery, how many boxes remain in the warehouse?
A
2225 boxes
B
2245 boxes
C
2210 boxes
D
2275 boxes
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2225 boxes
Step-by-Step Explanation:
4500 - 2275 = 2225 boxes remain.
41
Short Answer
Medium
1 Mark
At the City Botanical Seed Distribution, staff collected 4500 items in Week 1 and 2275 items in Week 2. How many items were collected in total?
A
6775 items
B
6725 items
C
6875 items
D
6755 items
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
6775 items
Step-by-Step Explanation:
4500 + 2275 = 6775 items.
42
Multiple Choice
Easy
1 Mark
Evaluate: 4,000 - 1,250 =
A
2,750
B
2,850
C
3,750
D
2,650
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2,750
Step-by-Step Explanation:
4,000 - 1,250 = 2,750.
43
Multiple Choice
Easy
1 Mark
Estimate 3,890 + 2,120 by rounding each number to the nearest hundred:
A
6,000
B
5,900
C
6,100
D
5,800
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
6,000
Step-by-Step Explanation:
3,890 rounds to 3,900. 2,120 rounds to 2,100. 3,900 + 2,100 = 6,000.
44
Multiple Choice
Easy
1 Mark
Calculate: 4500 - 2275 =
A
2225
B
2235
C
2215
D
2325
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2225
Step-by-Step Explanation:
Subtract with regrouping: 4500 - 2275 = 2225.
45
Multiple Choice
Easy
1 Mark
Calculate: 4500 + 2275 =
A
6775
B
6765
C
6795
D
6675
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
6775
Step-by-Step Explanation:
Add with regrouping: 4500 + 2275 = 6775.
46
Short Answer
Hard
2 Marks
The sum of two 4-digit numbers is 8,240. If one number is 1,500 greater than the other, what is the smaller number?
A
3,370
B
3,470
C
4,870
D
3,270
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
3,370
Step-by-Step Explanation:
Subtract the difference first: 8,240 - 1,500 = 6,740. Divide equally between the two: 6,740 ÷ 2 = 3,370.
47
Short Answer
Hard
2 Marks
A charity fundraiser aimed to collect $7,500. On Monday they raised $2,840, on Tuesday $1,950, and on Wednesday $1,630. How much more money is needed to reach the goal?
A
$1,080
B
$1,180
C
$980
D
$1,280
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
$1,080
Step-by-Step Explanation:
Total raised = 2,840 + 1,950 + 1,630 = 6,420. Remaining needed = 7,500 - 6,420 = $1,080.
48
Short Answer
Hard
2 Marks
If the sum of two numbers is 5,000 and one number is 2,750, how can you find the other number?
A
Subtract 2,750 from 5,000 (5,000 - 2,750 = 2,250)
B
Add 5,000 + 2,750
C
Multiply 5,000 × 2,750
D
Divide 5,000 by 2
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Subtract 2,750 from 5,000 (5,000 - 2,750 = 2,250)
Step-by-Step Explanation:
Subtraction is the inverse of addition: Sum - Known Addend = Unknown Addend.
49
Short Answer
Hard
2 Marks
Why does subtracting 1 from both numbers in a problem like 5,000 - 2,347 (giving 4,999 - 2,346) produce the exact same correct answer without any borrowing?
A
Because shifting both numbers by the same amount preserves the exact difference between them, while 4,999 requires no borrowing across zeroes
B
Because 4,999 is an easy number to write
C
Because zeroes disappear in math
D
It only works on leap years
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Correct Answer:
Because shifting both numbers by the same amount preserves the exact difference between them, while 4,999 requires no borrowing across zeroes
Step-by-Step Explanation:
The difference between two values (a - b) remains identical if both values shift by the same constant: (a - 1) - (b - 1) = a - b.
50
Short Answer
Medium
1 Mark
Maya solves 2,400 - 1,150 = 1,350 and checks her work by adding 1,350 + 2,400 = 3,750. What is wrong with Maya's checking method?
A
To check subtraction, add the DIFFERENCE to the SUBTRAHEND (1,350 + 1,150 = 2,400), not to the minuend
B
Maya should check by dividing
C
Subtraction cannot be checked
D
Maya's subtraction was wrong
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
To check subtraction, add the DIFFERENCE to the SUBTRAHEND (1,350 + 1,150 = 2,400), not to the minuend
Step-by-Step Explanation:
Difference + Subtrahend = Minuend.