Class 9 Maths — Chapter 1: NUMBER SYSTEMS

What you'll learn

• ▸Classification of Number Systems
• ▸Rational Numbers (Q)
• ▸Relationships Between Number Systems
• ▸Finding Rational Numbers Between Two Numbers
• ▸Irrational Numbers
• ▸Real Numbers and the Number Line

Chapter Summary

--- PAGE 1 --- CHAPTER 1 NUMBER SYSTEMS 1.1 Introduction In your earlier classes, you have learnt about the number line and how to represent various types of numbers on it (see Fig. 1.1). -3 -2 -1 0 1/4 1/2 3/4 1 2 3 <---|----|----|---|----|---|----|---|---|---> Fig. 1.1 : The number line Just imagine you start from zero and go on walking along this number line in the positive direction. As far as your eyes can see, there are numbers, numbers and numbers! © not to be republished Fig. 1.2 Now suppose you start walking along the number line, and collecting some of the numbers. Get a bag ready to store them! Reprint 2025-26 --- PAGE 2 --- 2 MATHEMATICS You might begin with picking up only natural numbers like 1, 2, 3, and so on. You know that this list goes on for ever. (Why is this true?) So, now your bag contains infinitely many natural numbers! Recall that we denote this coll…

Practice Questions from this Chapter

Tap "Get Solution" on any question to ask our AI tutor.

1. Explain rational numbers simply. Get Solution →
2. Describe real-world uses for integers. Get Solution →
3. Compare counting numbers and whole numbers. Get Solution →
4. What is the name for the collection of numbers like 1, 2, 3, and so on, denoted by the symbol N? Get Solution →
5. When zero is added to the collection of natural numbers, what is the new collection called, denoted by the symbol W? Get Solution →
6. The collection of all positive numbers, negative numbers, and zero is denoted by the symbol Z. What is this collection called? Get Solution →
7. According to the definition in the text, a number 'r' is called a rational number if it can be written in what form? Get Solution →
8. The symbol Z for integers comes from the German word 'zahlen'. What does 'zahlen' mean? Get Solution →

Did you know?

• 💡 The number zero was independently invented in ancient India.
• 💡 There are more atoms in a glass of water than glasses of water in all Earth's oceans.
• 💡 The largest known prime number is too big to fit on a million pages.
• 💡 Computers only use two numbers, zero and one, for all their calculations.
• 💡 Ancient Roman numerals had no way to write the number zero.

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