Exercise 4.1 of Class 7 Maths Chapter 4 – Expressions Using Letter-Numbers teaches about using letters to stand for a number. In this exercise you will learn to write expressions with letters like x or y, but letters that will stand for numbers. The understanding from this exercise is based on patterns and rules. Doing these practice problems will help when you have to solve equations later.
The questions are prepared based on the most recent NCERT syllabus, which makes them important for your school exams. Equally, it will also give you a strong base for maths competitions like the olympiads and even for higher classes.
We also provide step-by-step NCERT Solutions which follow the CBSE guidelines to ensure proper preparation. Also, you can download the pdf solutions and practice them for free!
This exercise teaches students how to create expressions that use letters and numbers. The available NCERT Solutions for Class 7 Maths Chapter 4 provide easy to understand, concise and clear explanations for each and every question. Download the PDF from below:
The key concepts in exercise 4.1 was:
1. Write formulas for the perimeter of -
(a) triangle with all sides equal.
(b) a regular pentagon (as we have learnt last year, we use the word regular to say that all side lengths and angle measures are equal)
(c) a regular hexagon
Sol. (a) Let side length of each side of triangle =a So, perimeter of triangle with all sides equal =3a.
(b) Let side length of a regular pentagon =a So, perimeter of the regular pentagon =5a
(c) Let side length of a regular hexagon =a So, perimeter of the regular hexagon =6a
2. Munirathna has a 20 m long pipe. However, he wants a longer watering pipe for his garden. He joins another pipe of some length to this one. Give the expression for the combined length of the pipe. Use the letter-number 'k to denote the length in meters Of the Other pipe.
Sol. Length of pipe Munirathna has =20 m Length of another pipe he wants to join in meters =k The combined length of the pipe =(20+k)m
3. What is the total amount Krithika has, if she has the following numbers of notes of ₹100, ₹20 and ₹5? Complete the following table?
Sol.
4. Venkatalakshmi owns a flour mill. It takes 10 seconds for the roller mill to Start running. Once it is running, each kg of grain takes 8 seconds to grind into powder. Which of the expressions below describes the time taken to complete grind 'y' kg of grain, assuming the machine is off initially?
(a) 10+8+Y
(b) (10+8)×y
(c) 10×8×y
(d) 10+8×y
(e) 10×y+8
Sol. Time taken by the roller mill to start running 10 seconds Time taken by the roller mill to grind each kg of grain to powder =8 seconds Therefore, expression for the time taken to complete grind y kg of grain =10+8×y Thus, expression (d) 10+8× y describes the given condition.
5. Write algebraic expressions using letters of your choice.
(a) 5 more than a number
(b) 4 less than a n umber
(c) 2 less than 13 times a number
(d) 13 less than 2 times a number
Sol. Let letter ' n ' represents the number, then
(a) n+5
(b) n−4
(c) 13×n−2
(d) 2×n−13
6. Describe situations corresponding to the following algebraic expressions:
(a) 8×x+3×y
(b) 15×j−2×k
Sol. (a) Kritika bought x number of notebooks and y number of pencils. What is the total amount she has to pay to the shopkeeper, if the cost of each notebook is ₹8 and cost of each pencil is ₹3?
(b) Rohan earns ₹15 per glass by selling lemonade in his school fete. To maintain the cleanliness he further announced ₹2 discount on each glass, the customer return to him. If he sold j number of glasses and k number of glasses were returned to him, what is the total earnings at the end of the day?
7. In a calendar month, if any 2×3 grid full of dates is chosen as shown in the picture, write expressions for the dates in the blank cells if the bottom middle cell has date 'W'.
Sol.
These questions are based on real-life situations and sequences of numbers that are easy to follow.
(Session 2026 - 27)