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Number System

Rajasthan Board · Class 9 · Mathematics

Flashcards for Number System — Rajasthan Board Class 9 Mathematics. Quick Q&A cards covering key concepts, definitions, and formulas.

29 questions25 flashcards5 concepts
25 Flashcards
Card 1Rational Numbers

What is a rational number? Give the general form.

Answer

A rational number is any number that can be expressed in the form p/q, where p and q are integers and q ≠ 0. Examples: 3/4, -2/5, 7 (which is 7/1), 0 (which is 0/1).

Card 2Rational Numbers

Is zero a rational number? Justify your answer.

Answer

Yes, zero is a rational number because it can be written in the form p/q where p = 0 and q is any non-zero integer. For example: 0 = 0/1 = 0/2 = 0/3, etc.

Card 3Number Classification

True or False: Every whole number is a natural number. Give reason.

Answer

False. Every whole number is NOT a natural number because zero is a whole number but not a natural number. Natural numbers = {1, 2, 3, 4, ...} while Whole numbers = {0, 1, 2, 3, 4, ...}

Card 4Number Classification

True or False: Every integer is a rational number. Give reason.

Answer

True. Every integer m can be expressed in the form m/1, which is in the form p/q where p = m, q = 1, and q ≠ 0. Therefore, every integer is a rational number.

Card 5Rational Numbers

How do you find rational numbers between two given rational numbers?

Answer

Method 1: Find the average (r + s)/2 of the two numbers r and s. Method 2: Convert both numbers to have the same denominator (n+1 where n is the number of rational numbers needed), then list numbers w

Card 6Irrational Numbers

What is an irrational number? Give examples.

Answer

An irrational number is a real number that cannot be expressed in the form p/q where p and q are integers and q ≠ 0. These have non-terminating, non-recurring decimal expansions. Examples: √2, √3, π,

Card 7Irrational Numbers

How do you locate √2 on the number line?

Answer

Construct a right triangle with legs of length 1 unit each. By Pythagoras theorem, hypotenuse = √(1² + 1²) = √2. Place one vertex at origin O, use compass with center O and radius equal to hypotenuse

Card 8Irrational Numbers

Are the square roots of all positive integers irrational?

Answer

No. The square roots of perfect squares are rational. For example: √4 = 2, √9 = 3, √16 = 4, √25 = 5, etc. However, square roots of non-perfect squares like √2, √3, √5, √7, etc. are irrational.

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What are the important topics in Number System for Rajasthan Board Class 9 Mathematics?

Number System covers several key topics that are frequently asked in Rajasthan Board Class 9 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.

Start by understanding all key concepts. Practise previous year questions from this chapter. Revise formulas and definitions regularly. Use flashcards for quick revision before the exam.

There are 25 flashcards for Number System covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.