Number System


  1. If * is a digit such that 5824* is divisible by 11, then * equals :









  1. View Hint View Answer Discuss in Forum

    Any number is divisible by 11 when the differences of alternative digits is 0 or multiple of 0, 11 etc. Here,

    Correct Option: C

    Any number is divisible by 11 when the differences of alternative digits is 0 or multiple of 0, 11 etc. Here,

    Therefore , the place of * will come 5.


  1. If a number is divisible by both 11 and 13, then it must be necessarily :









  1. View Hint View Answer Discuss in Forum

    As we know that If a number is divisible by both 11 and 13, then it will be also divisible by multiple of both 11 and 13 .

    Correct Option: C

    As we know that If a number is divisible by both 11 and 13, then it will be also divisible by multiple of both 11 and 13 i.e.
    divisible by (11 × 13) .



  1. If the sum of the digits of any integer lying between 100 and 1000 is subtracted from the
    number, the result always is









  1. View Hint View Answer Discuss in Forum

    Number = 100p + 10q + r
    Sum of digits = p + q + r
    Difference = 100p + 10q + r – p – q – r

    Correct Option: C

    Number = 100p + 10q + r
    Sum of digits = p + q + r
    Difference = 100p + 10q + r – p – q – r
    Difference = 99p + 9q = 9 (11p + q)
    Therefore , required answer is 9 .


  1. If n is an integer, then (n3 – n) is always divisible by :









  1. View Hint View Answer Discuss in Forum

    n3 – n = n (n + 1) (n – 1)
    n = 1, n3 – n = 0
    n = 2, n3 – n = 2 × 3 = 6

    Correct Option: C

    n3 – n = n (n + 1) (n – 1)
    n = 1, n3 – n = 0
    n = 2, n3 – n = 2 × 3 = 6
    n = 3, n3 – n = 3 × 4 × 2 = 24
    n = 4, n3 – n = 4 × 5 × 3 = 60
    ⇒ 60 ÷ 6 = 10
    Hence , required answer is 6.



  1. If ‘n’ be any natural number, then by which largest number (n3 – n) is always divisible ?









  1. View Hint View Answer Discuss in Forum

    n3 – n = n (n2 – 1)
    n3 – n = n (n + 1) (n – 1)
    For n = 2, n3 – n

    Correct Option: B

    n3 – n = n (n2 – 1)
    n3 – n = n (n + 1) (n – 1)
    For n = 2, n3 – n
    ⇒ 23 – 2 = 8 - 2 = 6
    Hence , ( n3 – n ) is divisible by 6.