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Number System

Punjab Board · Class 9 · Mathematics

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

43 questions28 flashcards5 concepts

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A nested Venn diagram illustrating the relationships between natural numbers (N), integers (Z), rational numbers (Q), and real numbers (R) as subsets of each other.
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28 Flashcards
Card 1Rational Numbers

Is zero a rational number? Express it in the form p/q.

Answer

Yes, zero is a rational number. We can write it as 0/1, 0/2, 0/3, etc., where p = 0 and q ≠ 0. Since zero can be expressed as the ratio of two integers, it satisfies the definition of a rational numbe

Card 2Rational Numbers

Find five rational numbers between 3 and 4.

Answer

Method: Write 3 and 4 with denominator 6 (5+1): 3 = 18/6 and 4 = 24/6. The five numbers between them are: 19/6, 20/6 = 10/3, 21/6 = 7/2, 22/6 = 11/3, 23/6. Simplified answers: 19/6, 10/3, 7/2, 11/3, 2

Card 3Rational Numbers

Find three rational numbers between 3/5 and 4/5.

Answer

Method 1 - Midpoint method: Between 3/5 and 4/5, find (3/5 + 4/5)/2 = 7/10. Between 3/5 and 7/10, find (3/5 + 7/10)/2 = (6/10 + 7/10)/2 = 13/20. Between 7/10 and 4/5, find (7/10 + 4/5)/2 = (7/10 + 8/1

Card 4Classification of Numbers

Determine if these statements are true or false: (i) Every whole number is a natural number. (ii) Every integer is a whole number. (iii) Every rational number is a whole number.

Answer

(i) FALSE - Zero is a whole number but NOT a natural number. Natural numbers = {1, 2, 3, ...}, Whole numbers = {0, 1, 2, 3, ...}. (ii) FALSE - Negative integers like -5, -10 are NOT whole numbers. Who

Card 5Decimal Expansions of Rational Numbers

Convert 10/3 to decimal form and describe its pattern.

Answer

Performing long division: 10 ÷ 3 = 3.333... The pattern shows: Remainder 1 repeats indefinitely. Decimal form: 10/3 = 3.3̄ (bar over 3 indicates repetition). This is a non-terminating recurring decima

Card 6Decimal Expansions of Rational Numbers

Convert 1/7 to decimal form and identify the repeating block.

Answer

Performing long division: 1 ÷ 7 = 0.142857142857... Step-by-step remainders: 1→10→3→2→6→4→5→1 (cycle repeats). Decimal form: 1/7 = 0.1̄4̄2̄8̄5̄7̄ (bar over all six digits). Repeating block: 142857 (pe

Card 7Decimal Expansions of Rational Numbers

Convert 7/8 to decimal and explain why it terminates.

Answer

Performing long division: 7 ÷ 8 = 0.875 Remainders: 7→2→4→0 (stops here). Decimal form: 7/8 = 0.875 (terminating). Why it terminates? The denominator 8 = 2³, which is a power of 2 only. Rule: A fracti

Card 8Converting Recurring Decimals to Fractions

Express 0.3̄ (where 3 repeats) as a fraction p/q.

Answer

Let x = 0.3̄ = 0.3333... Step 1: Multiply by 10 → 10x = 3.3333... Step 2: Notice that 10x = 3 + 0.3333... = 3 + x Step 3: Solve → 10x - x = 3 → 9x = 3 → x = 3/9 = 1/3 Answer: 0.3̄ = 1/3 Verification:

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Frequently Asked Questions

What are the important topics in Number System for Punjab Board Class 9 Mathematics?
Key topics in Number System include Real Number System Classification, Number System Classification and Relationships, A mind map showing the hierarchical classification of the real number system, illustrating how each category is nested within the larger categories. These are the concepts Punjab Board Class 9 examiners draw on most — study them first, then practise related questions.
How to score full marks in Number System — Punjab Board Class 9 Mathematics?
Understand the core concepts first, then work through the 43 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.
How many flashcards are available for Number System?
There are 28 flashcards for Number System covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.

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

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