Parts and Wholes — Class 5 Mathematics (CBSE)
Based on the NCERT Math Magic Grade 5 textbook. Understand how fractions represent parts of a whole, then solve the practice set without looking at the answers.
1. Why this chapter matters
Fractions are everywhere — half a glass of water, a quarter of a chocolate bar, three-fourths of a pizza. This chapter builds a solid understanding of fractions: what they mean, how to compare them, how to find equivalent fractions, and how to add and subtract them. Students also learn to find a fraction of a collection (for example, one-third of 12 apples) and solve real-world word problems. This lays the groundwork for decimals, percentages, ratios, and algebra in higher classes.
2. What is a fraction?
A fraction represents a part of a whole. It has two parts:
- Numerator: The number of parts we have (top number).
- Denominator: The total number of equal parts the whole is divided into (bottom number).
Example: In the fraction 3/4 (three-fourths), the whole is divided into 4 equal parts and we take 3 of them.
Types of fractions
| Type | Description | Example |
|---|---|---|
| Proper fraction | Numerator < Denominator | 2/5, 3/8, 7/12 |
| Improper fraction | Numerator > Denominator | 7/3, 11/4, 5/2 |
| Mixed fraction | Whole number + proper fraction | 1 1/2, 2 3/4, 3 1/3 |
| Like fractions | Fractions with same denominator | 2/7, 4/7, 5/7 |
| Unlike fractions | Fractions with different denominators | 2/3, 5/8, 7/12 |
| Unit fraction | Numerator is 1 | 1/2, 1/3, 1/4, 1/5 |
| Equivalent fractions | Different fractions with same value | 1/2 = 2/4 = 3/6 = 4/8 |
3. Equivalent fractions
Equivalent fractions look different but represent the same amount.
To get an equivalent fraction, multiply or divide the numerator and denominator by the same number (except zero).
Example: Find three equivalent fractions for 2/3.
2/3 = (2 x 2)/(3 x 2) = 4/6 2/3 = (2 x 3)/(3 x 3) = 6/9 2/3 = (2 x 4)/(3 x 4) = 8/12
Example: Find an equivalent fraction for 8/12 by simplifying.
8/12 = (8 / 4)/(12 / 4) = 2/3
The simplest form of 8/12 is 2/3.
4. Comparing fractions
Rule 1: Same denominator
If denominators are the same, the fraction with the larger numerator is larger.
Example: 5/8 > 3/8 (because 5 > 3)
Rule 2: Same numerator
If numerators are the same, the fraction with the smaller denominator is larger.
Example: 3/4 > 3/8 (because 4 < 8, so the parts are bigger)
Rule 3: Different numerators and denominators
Make the denominators the same (find LCM), then compare numerators.
Example: Compare 2/3 and 3/5.
LCM of 3 and 5 = 15 2/3 = 10/15 3/5 = 9/15 Since 10/15 > 9/15, we have 2/3 > 3/5.
5. Addition and subtraction of like fractions
When denominators are the same, add or subtract only the numerators.
- 3/8 + 2/8 = (3 + 2)/8 = 5/8
- 7/12 — 4/12 = (7 — 4)/12 = 3/12 = 1/4 (simplify)
When denominators are different, first convert to equivalent fractions with a common denominator.
- 1/2 + 1/3 = 3/6 + 2/6 = 5/6
- 3/4 — 1/3 = 9/12 — 4/12 = 5/12
Word problem: Ravi ate 1/4 of a pizza and Sita ate 2/5 of the same pizza. How much did they eat together?
1/4 + 2/5 = 5/20 + 8/20 = 13/20
6. Fraction of a collection
To find a fraction of a collection, divide the total by the denominator and multiply by the numerator.
Example: Find 2/3 of 24 apples.
Step 1: 24 / 3 = 8 (one-third of 24) Step 2: 8 x 2 = 16 (two-thirds of 24)
So 2/3 of 24 apples = 16 apples.
Example: Find 3/4 of 20 marbles.
Step 1: 20 / 4 = 5 Step 2: 5 x 3 = 15
So 3/4 of 20 marbles = 15 marbles.
7. Mixed fractions
A mixed fraction combines a whole number and a proper fraction.
Converting mixed to improper: Multiply the whole number by the denominator, then add the numerator.
2 1/3 = (2 x 3 + 1)/3 = 7/3
Converting improper to mixed: Divide the numerator by the denominator. The quotient is the whole number, the remainder is the numerator.
7/3 = 2 remainder 1 = 2 1/3
8. Word problems
Problem 1: A chocolate bar has 12 pieces. Rohan ate 1/3 of it. How many pieces did he eat?
12 / 3 = 4 pieces
Problem 2: Meera read 3/5 of a 25-page story. How many pages did she read?
25 / 5 = 5, then 5 x 3 = 15 pages
Problem 3: A farmer has 60 cows. 1/4 are black and the rest are white. How many are white?
Black cows = 60 / 4 = 15. White cows = 60 — 15 = 45.
9. Activity corner
Activity 1: Take a paper rectangle. Fold it into 4 equal parts. Colour 1 part red, 2 parts blue, and 1 part green. Write the fraction for each colour.
Activity 2: Take 20 objects (buttons, beads, stones). Find 1/2 of 20, 1/4 of 20, 3/4 of 20, 2/5 of 20. Record your answers.
Activity 3: Draw a rectangle on a grid of 12 squares. Colour 1/2 of it one colour and 1/3 another colour. How many squares of each colour?
10. Common mistakes
- Mistake: Adding both numerators and denominators (2/5 + 1/5 = 3/10 instead of 3/5) Fix: When adding like fractions, add only the numerators. The denominator stays the same.
- Mistake: Thinking a larger denominator always means a larger fraction Fix: When numerators are the same, a smaller denominator means a larger fraction (because each part is bigger).
- Mistake: Forgetting to simplify the final answer Fix: Always check whether the answer can be reduced to its simplest form.
11. Key facts
- Fraction = part of a whole (numerator / denominator).
- Equivalent fractions are made by multiplying or dividing both parts by the same number.
- To compare unlike fractions, find a common denominator first.
- To find a fraction of a collection: divide by denominator, multiply by numerator.
- Always simplify fractions to their lowest terms.
- A mixed fraction has a whole number and a proper fraction.
12. Self-test
- Write three equivalent fractions for 1/3.
- Which is larger: 3/7 or 5/7? Explain why.
- Find 3/5 of 30 mangoes.
- Add: 2/9 + 4/9. Simplify your answer.
- A ribbon is 24 cm long. Priya uses 3/8 of it. How much ribbon does she use?
13. Answer key
-
Write three equivalent fractions for 1/3. Answer: 2/6, 3/9, 4/12 (or any fraction where numerator and denominator are multiplied by the same number).
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Which is larger: 3/7 or 5/7? Explain why. Answer: 5/7 is larger. When denominators are the same (both 7), the larger numerator means the larger fraction (5 > 3).
-
Find 3/5 of 30 mangoes. Answer: 30 / 5 = 6. 6 x 3 = 18 mangoes.
-
Add: 2/9 + 4/9. Simplify your answer. Answer: (2 + 4)/9 = 6/9 = 2/3.
-
A ribbon is 24 cm long. Priya uses 3/8 of it. How much ribbon does she use? Answer: 24 / 8 = 3. 3 x 3 = 9 cm.
14. Quick revision
- A fraction has a numerator (parts taken) and denominator (total parts).
- Equivalent fractions = same value, different numbers.
- Compare: same denominator = compare numerators. Same numerator = compare denominators.
- Add/subtract: same denominator first, then work on numerators.
- Fraction of a collection = (Total / Denominator) x Numerator.
- Practise with real objects (chapatis, chocolates, fruits) to build understanding.
