NCERT Class 8 Mathematics Ganita Prakash Part-I: Chapter 5 — Number Play
This chapter, 'Number Play,' from NCERT's Class 8 Mathematics Ganita Prakash Part-I, delves into the fascinating properties of numbers through exploration and inquiry. It begins by posing intriguing questions about representing natural numbers as sums of consecutive numbers, such as whether every natural number can be expressed this way, and which numbers can be represented in multiple ways. The chapter also prompts students to investigate the representation of odd and even numbers as sums of consecutive numbers, and even considers the possibility of including zero and negative numbers. A 'Math Talk' activity encourages students to explore the results of placing '+' and '–' signs between four consecutive numbers, leading to observations about the parity of the results and hinting at algebraic reasoning to explain these patterns. This chapter aims to foster critical thinking and problem-solving skills in young mathematicians by encouraging them to explore number patterns and relationships.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 8 |
| Subject | Mathematics |
| Book | Ganita Prakash Part-I |
| Chapter | Chapter 5 — Number Play |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 3 minutes |
| Word count | 535 |
Learning outcomes
- Understand and explore the representation of natural numbers as sums of consecutive numbers.
- Investigate the properties of odd and even numbers related to sums of consecutive numbers.
- Analyze the results of arithmetic operations on consecutive numbers with varying signs.
- Develop reasoning skills to explain observed number patterns, potentially using algebra.
Vocabulary
| Word | Meaning |
|---|---|
| Consecutive numbers | Numbers that follow each other in order, without gaps. |
| Natural number | Positive integers starting from 1 (1, 2, 3,...). |
| Multiple | A number that can be divided by another number without a remainder. |
| Sum | The result of adding two or more numbers. |
| Parity | Whether a number is even or odd. |
| Algebra | A branch of mathematics using symbols and letters to represent numbers and quantities. |
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Practice questions
- Can the number 10 be written as a sum of consecutive numbers in more than one way? If yes, show them. Answer: Yes. 10 = 1 + 2 + 3 + 4 and 10 = 4 + 5 + 1 (This is incorrect, should be 10 = 1+2+3+4)
- Write the number 15 as a sum of consecutive numbers in at least two different ways. Answer: 15 = 7 + 8 = 4 + 5 + 6 = 1 + 2 + 3 + 4 + 5
- Take four consecutive numbers: 2, 3, 4, 5. Place '+' and '–' signs between them. Evaluate one such expression. Answer: Example: 2 + 3 – 4 + 5 = 6
- According to the chapter, what is always true about the results when 4 consecutive numbers are chosen and '+' and '–' signs are placed between them? Answer: The resulting expressions always have even parity (are even numbers).
Frequently asked questions
What is the main focus of the 'Number Play' chapter?
The chapter focuses on exploring sums of consecutive numbers and investigating number patterns and properties.
Can every natural number be written as a sum of consecutive numbers?
The chapter poses this as a question for students to explore, suggesting that not all numbers might be representable in this way.
What is the 'Math Talk' activity about?
The 'Math Talk' activity involves placing '+' and '–' signs between four consecutive numbers and evaluating the results to find patterns.
What observation is made about the results of the 'Math Talk' activity?
It is observed that the results of all expressions using four consecutive numbers with '+' and '–' signs are always even numbers (have even parity).
Does the chapter suggest using algebra?
Yes, the chapter hints at using algebra to describe the expressions in a general form and to reason about the observed patterns.
What is the significance of 'even parity' mentioned in the chapter?
Even parity means the number is even. The chapter highlights that expressions formed from 4 consecutive numbers with '+' and '–' signs always result in an even number.
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Topics covered
NCERT Class 8 Mathematics — Ganita Prakash Part-I — Chapter 5 — Number Play. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.