Class 7 Maths Part 1 Chapter 4, Expressions using Letter-Numbers, introduces algebra through letter-numbers (variables) that concisely express relationships, geometry formulas, calendar grids and matchstick growth patterns, and teaches how to simplify algebraic expressions by combining like terms.
What Class 7 Mathematics Chapter 4 Covers
4.1–4.3 The Notion of Letter-Numbers & Algebraic Notation uses letters ($a, n, x, l, b$) to write general relationships and perimeter/area formulas, evaluates expressions by substituting numbers, and introduces the convention of omitting the multiplication sign ($5n$ for $5 \times n$).
4.4 Simplification of Algebraic Expressions combines like terms using the distributive property (e.g., $4x + 3x = 7x$), removes brackets carefully, and spots common algebraic errors (‘Mind the Mistake, Mend the Mistake’).
4.5 Pick Patterns and Reveal Relationships writes and proves algebraic formulas for repeating design sequences, $2 \times 2$ calendar squares, and matchstick triangle/square patterns.
Exercises in Chapter 4
- Figure it Out exercise sets and Summary with solved walkthroughs.
Read Class 7 Mathematics Chapter 4 Online
More Chapters
- Previous: Chapter 3: A Peek Beyond the Point
- Next: Chapter 5: Parallel and Intersecting Lines
- Hindi medium: Class 7 Maths Part 1 Chapter 4 PDF in Hindi (Ganita Prakash)
- All Mathematics chapters and the other Class 7 books: Class 7 NCERT books 2026-27
FAQ
Why is 5n + 3 not equal to 8n?
In $5n + 3$, $5n$ means $5 \times n$ while $3$ is a constant term without $n$. Only like terms containing the same letter-number (such as $5n + 3n = 8n$) can be combined.
How do letter-numbers explain why the diagonal sums in a 2×2 calendar square are always equal?
If the top-left date is $a$, the other three dates in the $2 \times 2$ square are $a+1$, $a+7$, and $a+8$. Both diagonal sums simplify to $a + (a+8) = 2a + 8$ and $(a+1) + (a+7) = 2a + 8$, proving they are always equal.