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Computation and Operations - Long Division with Remainders

Grade 4IB

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

Long Division is a step-by-step method used to divide a large number (the dividend) by a smaller number (the divisor). Visually, imagine the dividend placed inside a 'division house' or bracket \lceil while the divisor stands outside on the left.

The Division Cycle follows the acronym DMSB: Divide, Multiply, Subtract, and Bring Down. You can visualize this as a repeating loop where you process the dividend one digit at a time, moving from left to right.

The Dividend is the total amount you have to share, and the Divisor is the number of groups you are making. The result you write on top of the bracket is called the Quotient, which represents the size of each group.

The Remainder (RR) is the 'leftover' amount that is not enough to form another equal group. Visually, the remainder is the very last number you calculate at the bottom of the long division process after all digits have been brought down.

The Remainder Rule states that the remainder must always be smaller than the divisor (R<divisorR < \text{divisor}). If the number at the bottom is equal to or larger than the divisor, it means the division is not finished yet.

Place Value alignment is essential for accuracy. You must write each digit of the quotient directly above the corresponding digit of the dividend. If a divisor cannot go into a digit, you must place a 00 as a placeholder in the quotient to keep the columns straight.

Checking your work involves using inverse operations. You can verify your answer by visualizing the relationship: (Groups ×\times Size) + Leftovers = Total. If (Quotient×Divisor)+Remainder=Dividend(\text{Quotient} \times \text{Divisor}) + \text{Remainder} = \text{Dividend}, your answer is correct.

📐Formulae

Dividend=(Divisor×Quotient)+Remainder\text{Dividend} = (\text{Divisor} \times \text{Quotient}) + \text{Remainder}

Remainder<Divisor\text{Remainder} < \text{Divisor}

Dividend÷Divisor=Quotient R Remainder\text{Dividend} \div \text{Divisor} = \text{Quotient} \text{ R } \text{Remainder}

💡Examples

Problem 1:

Find the quotient and remainder for 745÷4745 \div 4.

Solution:

  1. Divide the hundreds: 7÷4=17 \div 4 = 1. Write 11 on top. Multiply 1×4=41 \times 4 = 4. Subtract 74=37 - 4 = 3. \ 2. Bring down the 44 to make 3434. \ 3. Divide the tens: 34÷4=834 \div 4 = 8. Write 88 on top. Multiply 8×4=328 \times 4 = 32. Subtract 3432=234 - 32 = 2. \ 4. Bring down the 55 to make 2525. \ 5. Divide the ones: 25÷4=625 \div 4 = 6. Write 66 on top. Multiply 6×4=246 \times 4 = 24. Subtract 2524=125 - 24 = 1. \ 6. The answer is 186 R 1186 \text{ R } 1.

Explanation:

We use the DMSB steps for each place value. Since 11 is less than 44, we can no longer divide, making 11 our remainder.

Problem 2:

Solve 512÷5512 \div 5 and check your answer.

Solution:

  1. Divide 55 by 5=15 = 1. Write 11 on top. 1×5=51 \times 5 = 5. 55=05 - 5 = 0. \ 2. Bring down the 11. \ 3. Divide 11 by 5=05 = 0. Write 00 on top as a placeholder. 0×5=00 \times 5 = 0. 10=11 - 0 = 1. \ 4. Bring down the 22 to make 1212. \ 5. Divide 1212 by 5=25 = 2. Write 22 on top. 2×5=102 \times 5 = 10. 1210=212 - 10 = 2. \ 6. Result: 102 R 2102 \text{ R } 2. \ 7. Check: (102×5)+2=510+2=512(102 \times 5) + 2 = 510 + 2 = 512.

Explanation:

This example highlights the importance of the 00 placeholder in the tens column. Without it, the quotient would incorrectly be 1212 instead of 102102.