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Can We Share? - Division as Repeated Subtraction

Grade 3CBSE

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

🔑Concepts

Division as Equal Sharing: Division means distributing a total number of items into equal groups. For example, if you have 1212 buttons and share them equally among 33 shirts, you can visualize 33 circles representing the shirts and place 44 dots in each circle until all 1212 are used.

Division as Repeated Subtraction: Division is the process of subtracting the same number over and over again until you reach zero. For instance, to solve 10÷210 \div 2, you subtract 22 from 1010 repeatedly (102=810-2=8, 82=68-2=6, 62=46-2=4, 42=24-2=2, 22=02-2=0). Since you subtracted 55 times, the answer is 55.

The Division Symbol: We use the symbol ÷\div to represent division. In the equation 15÷3=515 \div 3 = 5, the symbol tells us to split 1515 into 33 equal groups.

Terms in Division: There are three main parts to a division sentence. The total amount being divided is the 'Dividend', the number we are dividing by is the 'Divisor', and the answer is the 'Quotient'. Visualise this as: Dividend÷Divisor=QuotientDividend \div Divisor = Quotient.

Relation with Multiplication: Division is the inverse (opposite) of multiplication. If you know that 4×5=204 \times 5 = 20, you can easily find that 20÷4=520 \div 4 = 5 and 20÷5=420 \div 5 = 4. You can imagine a 'Fact Family' triangle with 2020 at the top and 44 and 55 at the bottom corners.

Division by 1: When any number is divided by 11, the quotient is always the number itself. For example, 8÷1=88 \div 1 = 8. This is like having 88 sweets and giving them all to 11 person.

Division by the Same Number: When a number is divided by itself, the quotient is always 11. For example, 5÷5=15 \div 5 = 1. This is like sharing 55 pencils among 55 children; each child gets exactly 11 pencil.

Grouping on a Number Line: Division can be seen as taking equal jumps backward on a number line starting from the dividend. To solve 12÷412 \div 4, start at 1212 and take jumps of 44 backwards (1284012 \rightarrow 8 \rightarrow 4 \rightarrow 0). The total number of jumps (which is 33) is your answer.

📐Formulae

Dividend÷Divisor=QuotientDividend \div Divisor = Quotient

Dividend=Divisor×QuotientDividend = Divisor \times Quotient

abbb...(n times)=0    a÷b=na - b - b - b... (n \text{ times}) = 0 \implies a \div b = n

n÷1=nn \div 1 = n

n÷n=1n \div n = 1

💡Examples

Problem 1:

Use repeated subtraction to find the result of 15÷315 \div 3.

Solution:

Step 1: Subtract 33 from 1515: 153=1215 - 3 = 12 (1st time)\Step 2: Subtract 33 from 1212: 123=912 - 3 = 9 (2nd time)\Step 3: Subtract 33 from 99: 93=69 - 3 = 6 (3rd time)\Step 4: Subtract 33 from 66: 63=36 - 3 = 3 (4th time)\Step 5: Subtract 33 from 33: 33=03 - 3 = 0 (5th time)\Since we subtracted 33 exactly 55 times to reach zero, 15÷3=515 \div 3 = 5.

Explanation:

This method shows division as a process of taking away the same group size repeatedly until nothing is left.

Problem 2:

Rohan has 2424 marbles. He wants to put them into packets of 66 marbles each. How many packets will he need?

Solution:

Total marbles (Dividend) = 2424\Marbles per packet (Divisor) = 66\We need to find the number of packets (Quotient).\Using the multiplication table of 66: 6×1=66 \times 1 = 6, 6×2=126 \times 2 = 12, 6×3=186 \times 3 = 18, 6×4=246 \times 4 = 24.\Therefore, 24÷6=424 \div 6 = 4.

Explanation:

This problem uses division as equal grouping. By knowing multiplication facts, we can quickly find how many groups of 66 fit into 2424.