In Class 9 Math Ch 1 Number Systems Ex 1.4, students explore different types of numbers that form the foundation of mathematics. It covers real numbers, including natural numbers, whole numbers, integers, rational numbers, and irrational numbers. The chapter also explains the representation of numbers on the number line, the properties of operations like addition, subtraction, multiplication, and division, and how these numbers relate to each other. A key focus is understanding the decimal expansion of irrational numbers and the concept of real numbers being a combination of both rational and irrational numbers.
Class 9 Math Ch 1 Number Systems Ex 1.4 Textbook – Full Exercise
Question 1.


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The concept of visualizing decimal numbers on the number line plays a significant role in understanding the structure of the number system. In Class 9 Math Ch 1 Number Systems Ex 1.4, students are introduced to the idea of successive magnification, which allows them to plot numbers that have long or repeating decimal expansions.
Through the visualisation of numbers like 3.765 and 4.26̅, learners develop the ability to place non-terminating decimal numbers on the number line. This builds an intuitive grasp of the real number system. Class 9 Math Ch 1 Number Systems Ex 1.4 effectively demonstrates that even though some numbers have infinite decimal places, they still hold a specific and exact position on the number line.
Understanding these concepts is essential for higher mathematics where irrational numbers, limits, and continuity play a vital role. With Class 9 Math Ch 1 Number Systems Ex 1.4, CBSE introduces the idea that mathematics isn’t just about arithmetic or solving equations — it’s also about understanding how numbers behave, how they can be represented, and how they exist logically in space.
By working through Class 9 Math Ch 1 Number Systems Ex 1.4, students gain hands-on experience in estimating values through intervals and sub-intervals. This builds their analytical thinking and strengthens the foundational skills necessary for algebra, geometry, and real analysis in higher classes.
In conclusion, Class 9 Math Ch 1 Number Systems Ex 1.4 is not only a practical activity but also a stepping stone to more abstract mathematical thinking. It helps students connect numbers with their graphical representation and deepens their understanding of the number line as a continuous and infinite system.