Long Division: A method for dividing large numbers by breaking the problem into simpler steps: divide, multiply, subtract, bring down.
- Divide the first digit(s) of the dividend by the divisor
- Multiply the quotient by the divisor
- Subtract the result from the dividend
- Bring down the next digit
- Repeat until all digits are used
8 ÷ 4 = 2, write 2 above the 8
2 × 4 = 8, write 8 below the 8
8 - 8 = 0
Now divide 4 by 4 = 1, write 1 above the 4
1 × 4 = 4, then 4 - 4 = 0
84 ÷ 4 = 21
• DMBS: Divide, Multiply, Subtract, Bring Down
• Verification: Quotient × Divisor = Dividend
• Place value: Align digits properly in columns
Divisibility Rules: Quick ways to determine if a number can be divided evenly by another number without doing the full calculation.
Rule: Number must be divisible by both 2 and 3
156 is even (divisible by 2), sum of digits: 1+5+6=12 (divisible by 3)
156 ÷ 6 = 26
15 ÷ 6 = 2 remainder 3, write 2 above the 5
Make 36, then 36 ÷ 6 = 6
2 × 6 = 12, 15-12=3, bring down 6 to make 36, 36÷6=6
156 ÷ 6 = 26
• Divisibility by 6: Must be divisible by both 2 and 3
• Divisibility by 2: Number ends in 0, 2, 4, 6, or 8
• Divisibility by 3: Sum of digits is divisible by 3
Multiple Answer Forms: Division results can be expressed as quotient with remainder, decimal, or mixed number.
247 ÷ 5 = 49 R2
2 ÷ 5 = 0.4, so 49 R2 = 49.4
49 R2 = 49 2/5
49 × 5 = 245, 245 + 2 = 247 ✓
49.4 × 5 = 247 ✓
247 ÷ 5 = 49 R2 (with remainder), 49.4 (decimal), or 49 2/5 (mixed number)
• Remainder conversion: Remainder ÷ divisor = decimal part
• Fraction form: Quotient + (remainder/divisor)
• Verification: Always check with multiplication
Division: The mathematical operation that splits a number into equal groups or shares it equally.
Dividend: The number being divided (the whole amount).
Divisor: The number we divide by (tells us how many groups or how many in each group).
Quotient: The answer to a division problem (how many in each group or how many groups).
Remainder: What's left over when division doesn't result in equal groups (remainder is always less than the divisor).
Long Division: A systematic method for dividing larger numbers using the steps: Divide, Multiply, Subtract, Bring Down.
Divisibility Rules: Quick tests to determine if a number can be divided evenly by another number.
• Division is inverse of multiplication: If 3 × 4 = 12, then 12 ÷ 3 = 4 and 12 ÷ 4 = 3
• Division by 1: Any number divided by 1 equals itself (a ÷ 1 = a)
• Division by itself: Any non-zero number divided by itself equals 1 (a ÷ a = 1)
• Division by 0: Cannot divide by zero (undefined)
• Zero divided by a number: 0 ÷ a = 0 (for any non-zero a)
• Remainder rule: The remainder is always less than the divisor
• DMBS: Long division follows the pattern: Divide, Multiply, Subtract, Bring Down
- Identify the problem: Read the division sentence (e.g., 124 ÷ 4)
- Set up long division: Write dividend inside bracket, divisor outside
- Divide: How many times does divisor go into first digit(s)?
- Multiply: Multiply quotient by divisor
- Subtract: Subtract result from dividend
- Bring down: Bring down next digit
- Repeat: Continue until all digits are used
- Verify: Multiply quotient by divisor to check your answer
- Partial Quotients: Break the division into smaller, easier parts
- Estimation first: Round numbers to estimate before calculating precisely
- Using multiples: Find multiples of the divisor to make division easier
- Checking work: Always verify with multiplication
Fact Families: Sets of related multiplication and division facts using the same numbers (e.g., 4×6=24, 6×4=24, 24÷4=6, 24÷6=4)
Remainders: In class 4, students learn to convert remainders to decimals and fractions.
Word Problems: Complex problems requiring multiple steps including division.
Estimation: Using rounding to estimate division results before calculating precisely.
- Long Division: Systematic method for dividing large numbers
- Partial Quotients: Break the dividend into smaller parts
- Repeated Subtraction: Keep subtracting the divisor until reaching zero or remainder
- Fact Families: Use known multiplication facts to solve division problems
- Estimation: Round numbers to make division easier
- Using Multiples: Find multiples of the divisor to make division faster
• Division by 1: a ÷ 1 = a (any number divided by 1 is itself)
• Division by itself: a ÷ a = 1 (any non-zero number divided by itself is 1)
• Zero rule: 0 ÷ a = 0 (zero divided by any number is zero)
• Inverse relationship: If a × b = c, then c ÷ a = b and c ÷ b = a
• Remainder rule: Remainder must always be smaller than the divisor
• Verification: (Quotient × Divisor) + Remainder = Dividend
• Decimal conversion: Remainder ÷ Divisor = decimal part
Common Questions About Division
Question: I don't understand why we need to learn long division. Can't we just use a calculator?
Answer: Long division is important for several reasons:
- Understanding: It helps you understand how division really works
- Problem-solving: Builds logical thinking and step-by-step reasoning skills
- Foundation: Prepares you for more advanced math like algebra
- Checking: You can verify calculator answers when needed
- Tests: You may not always have a calculator available
Long division teaches patience and precision - valuable life skills!
Question: My child is struggling with the long division algorithm. How can I help them remember the steps?
Answer: Here are memory aids for the long division steps:
- DMBS: Remember "Does McDonald's Sell Burgers?" - Divide, Multiply, Subtract, Bring Down
- Visual cues: Write the letters DMBS at the top of the problem
- Practice with smaller numbers: Start with 2-digit dividends before moving to larger numbers
- Check each step: Verify each multiplication and subtraction before proceeding
- Use grid paper: Helps keep numbers aligned in columns
Consistent practice with guidance will build confidence!
Question: What are the most important divisibility rules for class 4 students to master?
These rules make division much faster and help verify answers!