Number System


  1. 216 –1 is divisible by









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    ∵ 216 – 1 = (28)2–1
    = (28+1) (28–1)

    Correct Option: C

    ∵ 216 – 1 = (28)2–1
    = (28+1) (28–1)
    = (256 + 1) (256 – 1)
    216 – 1 = 257 × 255 which is exactly divisible by 17.


  1. In a division sum, the divisor is 3 times the quotient and 6 times the remainder. If the remainder is 2, then the dividend is









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    According to question ,
    Divisor = 6 × Remainder
    Divisor = 6 × 2 = 12
    Again, Divisor = 3 × quotient

    ∴  Quotient =
    12
    = 4
    3

    Correct Option: A

    According to question ,
    Divisor = 6 × Remainder
    Divisor = 6 × 2 = 12
    Again, Divisor = 3 × quotient

    ∴  Quotient =
    12
    = 4
    3

    Dividend = 12 × 4 + 2
    Dividend = 48 + 2 = 50



  1. Two numbers 11284 and 7655, when divided by a certain number of three digits, leaves the
    same remainder. The sum of digits of such a three-digit number is









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    If the remainder be p, then (11284 – p ) and (7655 – p ) are divisible by three digit number.
    i.e. (11284 – p ) – (7655 – p ) = 3629 is divisible by that number.
    3629 = 19 × 191

    Correct Option: D

    If the remainder be p, then (11284 – p ) and (7655 – p ) are divisible by three digit number.
    i.e. (11284 – p ) – (7655 – p ) = 3629 is divisible by that number.
    3629 = 19 × 191
    Hence, required number = 191
    Sum of digits = 1 + 9 + 1 = 11


  1. When n is divided by 6, the remainder is 4. When 2n is divided by 6, the remainder is









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    According to question ,
    n = 6q + 4
    And 2n = 12q + 8

    Correct Option: A

    According to question ,
    n = 6q + 4
    And 2n = 12q + 8
    Dividing 8 by 6 the remainder = 2
    Hence required remainder = 2



  1. A number x when divided by 289 leaves 18 as the remainder. The same number when divided by 17 leaves y as a remainder. The value of y is









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    Here, the first divisor (289) is a multiple of second divisor (17).
    ∴ Required remainder = Remainder obtained on dividing 18 by 17

    Correct Option: D

    Here, the first divisor (289) is a multiple of second divisor (17).
    ∴ Required remainder = Remainder obtained on dividing 18 by 17 = 1
    Therefore required answer is 1.