Class 9 Mathematics — Chapter 3: The World of Numbers
90 practice questions · 30 Easy · 30 Medium · 30 Hard
Practise Class 9 Mathematics Chapter 3, "The World of Numbers", with 90 NCERT-aligned multiple-choice questions. The set is split into 30 Easy, 30 Medium and 30 Hard questions, so you can warm up on the fundamentals and then push into the exam-level problems that separate top scorers in CBSE Board exams and the JEE & NEET foundation years.
"The World of Numbers" is one of the chapters where problem-solving speed, formula recall and step-by-step reasoning really pays off. Each MCQ on this chapter is timed and uses exam-grade marking (+2 correct, −1 wrong, 0 skipped), training the same accuracy-under-pressure that real papers demand. Every question carries a short explanation, so a wrong answer becomes a quick lesson rather than a dead end — the fastest way to close gaps before a test.
Use this chapter as targeted revision: attempt the Easy set first to confirm your basics on The World of Numbers, then move to Medium and Hard to test application and problem-solving. Your accuracy, streaks and XP save automatically, and the chapter feeds into your overall Class 9 Mathematics mastery score. A few sample questions are shown below; sign in free to practise all 90.
Key concepts: The World of Numbers (Class 9 Mathematics)
This chapter introduces the Cartesian plane — how two perpendicular axes locate any point by an ordered pair, and how the plane splits into four quadrants.
- Cartesian plane
- Two perpendicular number lines: the horizontal x-axis and vertical y-axis, meeting at the origin O(0, 0).
- Coordinates of a point
- An ordered pair (x, y): x is the abscissa (distance from the y-axis), y is the ordinate (distance from the x-axis). Order matters.
- Quadrants
- The axes divide the plane into four quadrants with sign patterns I(+,+), II(−,+), III(−,−), IV(+,−).
- Points on the axes
- A point on the x-axis has y = 0, written (x, 0); a point on the y-axis has x = 0, written (0, y).
- Plotting points
- To plot (x, y), move x units along the x-axis, then y units parallel to the y-axis.
💡 Exam tips for The World of Numbers
- (x, y) and (y, x) are different points unless x = y — always keep the order.
- Read the sign pattern to identify the quadrant before plotting.
Sample questions
Which of the following is a rational number?
√16 = 4, which can be written as 4/1, so it is rational; √2, √5 and π are irrational.
Simplify 3/4 + 5/6 as a fraction in lowest terms.
3/4 + 5/6 = 9/12 + 10/12 = 19/12.
In proving √2 irrational, we write √2 = p/q in lowest terms. The contradiction reached is that:
From p² = 2q² one shows p is even, then q is even, so 2 divides both p and q — contradicting lowest terms.
The World of Numbers — FAQs
What are the key concepts in Class 9 Mathematics The World of Numbers?+
This chapter introduces the Cartesian plane — how two perpendicular axes locate any point by an ordered pair, and how the plane splits into four quadrants. Key ideas include Cartesian plane, Coordinates of a point, Quadrants, Points on the axes, Plotting points.
What does Class 9 Mathematics Chapter 3 (The World of Numbers) cover on XamBaaz?+
It covers 90 NCERT-aligned MCQs on "The World of Numbers" — 30 Easy, 30 Medium and 30 Hard — each with a timed quiz and an instant explanation, suitable for CBSE Board exams and the JEE & NEET foundation years.
Are these "The World of Numbers" questions free to practise?+
Yes — sign in with Google to practise "The World of Numbers" free. Full unlimited access is ₹999/year (limited-time launch price), with no per-chapter charges.
How should I revise "The World of Numbers" for the exam?+
Start with the Easy quiz to confirm your fundamentals, then attempt Medium and Hard for application-level practice. Review each explanation, retry the questions you miss, and track your accuracy on this chapter until it is consistently high.
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