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Number Systems

Karnataka Board · Class 9 · Mathematics

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

28 questions20 flashcards5 concepts
20 Flashcards
Card 1Decimal Expansions

Express 7/8 as a decimal. What type of decimal expansion is it?

Answer

Step 1: Divide 7 by 8 using long division: 0.875 8)7.000 64 --- 60 56 --- 40 40 --- 0 Step 2: Since remainder becomes 0, it's a terminating decimal. Answer: 7/8 = 0.875 (terminating

Card 2Decimal Expansions

Convert 0.333... (0.3̄) to the form p/q where p and q are integers.

Answer

Step 1: Let x = 0.333... Step 2: Multiply by 10: 10x = 3.333... Step 3: Subtract original equation: 10x - x = 3.333... - 0.333... Step 4: Simplify: 9x = 3 Step 5: Solve for x: x = 3/9 = 1/3 Answer: 0

Card 3Irrational Numbers

Is √25 rational or irrational? Justify your answer.

Answer

Step 1: Find the value of √25 √25 = 5 (since 5² = 25) Step 2: Check if 5 can be written as p/q 5 = 5/1, where p = 5, q = 1 (both integers, q ≠ 0) Step 3: Conclusion Since √25 = 5 can be expressed as

Card 4Rational Numbers

Find five rational numbers between 1/3 and 1/2.

Answer

Method: Convert to common denominator Step 1: LCM of 3 and 2 is 6 1/3 = 2/6 and 1/2 = 3/6 Step 2: Since we need 5 numbers, multiply by 10 1/3 = 20/60 and 1/2 = 30/60 Step 3: Find rational numbers be

Card 5Irrational Numbers

Show that 2 + √3 is an irrational number.

Answer

Proof by contradiction: Step 1: Assume 2 + √3 is rational Then 2 + √3 = p/q where p, q are integers, q ≠ 0 Step 2: Rearrange √3 = p/q - 2 = (p - 2q)/q Step 3: Analyze Since p, q are integers, (p - 2

Card 6Operations on Real Numbers

Simplify: (√5 + √2)(√5 - √2)

Answer

Step 1: Apply the identity (a + b)(a - b) = a² - b² Here, a = √5 and b = √2 Step 2: Substitute (√5 + √2)(√5 - √2) = (√5)² - (√2)² Step 3: Calculate = 5 - 2 = 3 Answer: 3

Card 7Operations on Real Numbers

Rationalise the denominator: 1/(3 + √2)

Answer

Step 1: Multiply numerator and denominator by conjugate (3 - √2) 1/(3 + √2) × (3 - √2)/(3 - √2) Step 2: Apply (a + b)(a - b) = a² - b² in denominator Numerator: 1 × (3 - √2) = 3 - √2 Denominator: (3

Card 8Decimal Expansions

Express 2.3̄7̄ (where 37 repeats) in the form p/q.

Answer

Step 1: Let x = 2.373737... Step 2: Since 2 digits repeat, multiply by 100 100x = 237.373737... Step 3: Subtract to eliminate repeating part 100x - x = 237.373737... - 2.373737... 99x = 235 Step 4:

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Frequently Asked Questions

What are the important topics in Number Systems for Karnataka Board Class 9 Mathematics?

Number Systems covers several key topics that are frequently asked in Karnataka 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 20 flashcards for Number Systems 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.