NCERT Class 7 Mathematics Ganita Prakash: Chapter 4 — Expressions using Letter-Numbers
This chapter introduces the concept of using letters to represent numbers in mathematics, known as letter-numbers. It explains how algebraic expressions are formed using these letter-numbers to represent mathematical relations and patterns concisely. For instance, Shabnam's age, being 3 years older than Aftab's age 'a', can be expressed as 'a + 3'. Similarly, the number of matchsticks needed for 'n' L-shapes, each requiring 2 matchsticks, is represented as '2 × n'. The chapter demonstrates how these expressions simplify calculations and help in understanding mathematical relationships. It emphasizes that letters like 'a' and 's' are variables that can stand for any number, forming the basis of algebraic expressions. This foundational understanding is crucial for further study in mathematics and problem-solving in CBSE curriculum.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 7 |
| Subject | Mathematics |
| Book | Ganita Prakash |
| Chapter | Chapter 4 — Expressions using Letter-Numbers |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 4 minutes |
| Word count | 602 |
Learning outcomes
- Understand the concept of letter-numbers as symbols representing unknown or variable quantities.
- Formulate algebraic expressions based on given mathematical relations.
- Use algebraic expressions to solve simple problems involving unknown quantities.
- Recognize the efficiency of using letters in mathematical notation.
- Differentiate between numerical expressions and algebraic expressions.
Vocabulary
| Word | Meaning |
|---|---|
| Letter-numbers | Letters used to represent numbers in mathematical expressions. |
| Algebraic expressions | Mathematical expressions containing letter-numbers, numbers, and operation signs. |
| Variable | A symbol (usually a letter) that can represent different numerical values. |
| Relation | A connection or correspondence between quantities. |
| Pattern | A regular or discernible form or order. |
The complete chapter text is read in the official NCERT PDF viewer below (streamed from ncert.nic.in). This page provides NCERT Help study material — summary, vocabulary, practice questions, and FAQs — not a full reproduction of the textbook.
Read chapter online
This PDF is loaded from the official NCERT website (ncert.nic.in). Use the page buttons below to read — download is disabled on NCERT Help.
Read page by page below. PDF is streamed from the official NCERT website — no download button on this page.
Practice questions
- If Shabnam's age is represented by 's' and Aftab's age by 'a', and Shabnam is 3 years older than Aftab, write the relation. Answer: s = a + 3
- If 'n' represents the number of L-shapes, and each L-shape needs 2 matchsticks, write the expression for the total number of matchsticks. Answer: 2 × n
- If Aftab's age 'a' is 15 years, what is Shabnam's age using the expression s = a + 3? Answer: 18 years
- Write an expression to find Shabnam's age if Aftab's age is 3 years less than Shabnam's age 's'. Answer: a = s - 3
Frequently asked questions
What are letter-numbers in mathematics?
Letter-numbers are letters used to represent numbers in mathematical expressions, allowing for concise representation of relationships and patterns.
What is an algebraic expression?
An algebraic expression is a mathematical phrase that contains numbers, variables (letter-numbers), and operation signs.
Why are letter-numbers used in mathematics?
They are used to express mathematical relations and patterns in a concise way, making it easier to think about, explain, and solve problems involving unknown quantities.
How do we find Shabnam's age if Aftab's age is known?
If Aftab's age is 'a' and Shabnam is 3 years older, Shabnam's age is found by the expression a + 3.
What is the relation between the number of Ls and matchsticks needed?
If 'n' is the number of Ls, and each L needs 2 matchsticks, the total number of matchsticks is 2 × n.
Can any letter be used as a letter-number?
Yes, typically any letter can be used to denote a number or a variable in mathematical expressions.
Related resources
Important topics
Topics covered
NCERT Class 7 Mathematics — Ganita Prakash — Chapter 4 — Expressions using Letter-Numbers. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.