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RRB NTPC Number System — practice questions

Explore 64 free Number System questions in RRB NTPC Quantitative Aptitude. Open each question or exercise to read its content, reference answers and available explanation.

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Number System questions and exercises with answers

Showing questions 1–30 of 64.

What is the square of 349?Read the answer and worked solution →Which of the following numbers is NOT a perfect cube?Read the answer and worked solution →If the number x3339 is divisible by 11, what is the digit x?Read the answer and worked solution →Which kind of number cannot be written as a ratio of two integers?Read the answer and worked solution →The square root of which of these numbers is irrational?Read the answer and worked solution →Which one of the following numbers is irrational?Read the answer and worked solution →What is true of the decimal expansion of an irrational number?Read the answer and worked solution →The ratio of a circle's circumference to its diameter is which number?Read the answer and worked solution →Between any two rational numbers, how many rational numbers lie?Read the answer and worked solution →Dividing one rational number by a nonzero rational number always gives what?Read the answer and worked solution →The decimal expansion of a rational number either terminates or does what?Read the answer and worked solution →What is the decimal form of the fraction 3/4?Read the answer and worked solution →Which fraction in lowest terms has a terminating decimal expansion?Read the answer and worked solution →A fraction in lowest terms terminates if its denominator has which prime factors only?Read the answer and worked solution →How many decimal places does the decimal expansion of 7/8 have?Read the answer and worked solution →The number √2 begins with which decimal digits?Read the answer and worked solution →Together, rational and irrational numbers make up which set?Read the answer and worked solution →Which process did Indian mathematicians develop for surds, removing a root from a denominator?Read the answer and worked solution →What is the smallest prime number?Read the answer and worked solution →Identify the composite number among these.Read the answer and worked solution →How many prime numbers are less than 20?Read the answer and worked solution →Counting upward from 1, which is the first composite number?Read the answer and worked solution →The fundamental theorem of arithmetic says every integer larger than 1 is what?Read the answer and worked solution →Break 60 into its prime factors.Read the answer and worked solution →Which pair consists of twin primes, primes differing by 2?Read the answer and worked solution →Which test shows that a number is divisible by 3?Read the answer and worked solution →Which number leaves no remainder when divided by 9?Read the answer and worked solution →What is the remainder when 492 is divided by 9?Read the answer and worked solution →For which number do the last two digits form a multiple of 4?Read the answer and worked solution →Which digit must the last place of a number have if it is divisible by 5?Read the answer and worked solution →

Worked practice questions

What is the square of 349?

  1. 122801
  2. 122881
  3. 121801
  4. 120801
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Correct answer: C. 121801

1. Write 349 as (350 − 1). 2. (350 − 1)² = 350² − 2·350 + 1 = 122500 − 700 + 1. 3. This equals 121801. _Source: RRB Group D (RRC) PYQ, held 27-10-2013, Q.18._

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Which of the following numbers is NOT a perfect cube?

  1. 64
  2. 243
  3. 216
  4. 1728
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Correct answer: B. 243

1. 64 = 4³, 216 = 6³ and 1728 = 12³, all perfect cubes. 2. For 243, note 6³ = 216 and 7³ = 343, so 243 lies between consecutive cubes. 3. Hence 243 is not a perfect cube (it is actually 3⁵). _Source: RRB Group D (RRC) PYQ, held 27-10-2013, Q.40._

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If the number x3339 is divisible by 11, what is the digit x?

  1. 2
  2. 4
  3. 5
  4. 3
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Correct answer: C. 5

1. Divisibility by 11: (sum of digits at odd places) - (sum at even places) is a multiple of 11. 2. For x3339, from the right: odd places 9, 3, x; even places 3, 3. Odd sum = 12 + x, even sum = 6. 3. Difference = 6 + x. For divisibility, 6 + x = 11, so x = 5. _Source: RRB Group D CEN-02/2018 PYQ, Q.71._

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