Number System
-  If * is a digit such that 5824* is divisible by 11, then * equals :
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                        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: CAny 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.
-  If a number is divisible by both 11 and 13, then it must be necessarily :
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                        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: CAs 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) .
-  If the sum of the digits of any integer lying between 100 and 1000 is subtracted from the
 number, the result always is
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                        View Hint View Answer Discuss in Forum Number = 100p + 10q + r 
 Sum of digits = p + q + r
 Difference = 100p + 10q + r – p – q – rCorrect Option: CNumber = 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 .
-  If n is an integer, then (n3 – n) is always divisible by :
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                        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 = 6Correct Option: Cn3 – 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.
-  If ‘n’ be any natural number, then by which largest number (n3 – n) is always divisible ?
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                        View Hint View Answer Discuss in Forum n3 – n = n (n2 – 1) 
 n3 – n = n (n + 1) (n – 1)
 For n = 2, n3 – nCorrect Option: Bn3 – 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.
 
	