Number System


  1. The number of all prime numbers less than 40 is ...









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    Prime number less than 40 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37

    Correct Option: C

    Prime number less than 40 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37
    ∴ The number of all prime numbers less than 40 = 12.


  1. The product of two consecutive number odd number is 6723. What is the greater number ?









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    Let the two consecutive odd number be (x + 1) and (x + 3).
    According to question (x + 1) (x + 3) = 6723

    Correct Option: D

    Let the two consecutive odd number be (x + 1) and (x + 3).
    According to question (x + 1) (x + 3) = 6723
    ⇒ x2 + 3x + x + 3 = 6723
    ⇒ x2 + 4x + 3 = 6723
    ⇒ x2 + 4x - 6720 = 0
    ⇒ x2 + 84x - 80x - 6720 = 0
    ⇒ ( x - 80 )( x + 84 )= 0
    ∴ x = 80, (x ≠ -84)
    Hence, the greater number = 80 + 3 = 83



  1. The sum of 4 consecutive even number is 284. What would be the smallest number ?









  1. View Hint View Answer Discuss in Forum

    Let four consecutive even numbers are x, x+2, x+4, x+6.
    According to the question
    ⇒ x + x+2 + x+4 + x+6 = 284

    Correct Option: C

    Let four consecutive even numbers are x, x+2, x+4, x+6.
    According to the question
    ⇒ x + x+2 + x+4 + x+6 = 284
    ⇒ 4x + 12 = 284
    ⇒ 4x = 272
    ∴ x = 272 / 4 = 68


  1. In the year 2011, Shantanu gets a total of 3832.5 Rupee as his pocket allowence. Find his pocket allowence per day.









  1. View Hint View Answer Discuss in Forum

    Allowance per day = total allowance / number of days in year

    Correct Option: B

    Allowance per day = total allowance / number of days in year
    = 3832.5 / 365
    = 10.5 Rupees



  1. The number of prime numbers between 0 and 50 is









  1. View Hint View Answer Discuss in Forum

    Prime numbers between 0 and 50 are 2 3 5 7 11 13 17 19 23 29 31 37 41 43 and 47

    Correct Option: C

    prime numbers between 0 and 50 are 2 3 5 7 11 13 17 19 23 29 31 37 41 43 and 47
    ∴ required number of prime number is 15