Number System
-  A number divided by 13 leaves a remainder 1 and if the quotient, thus obtained, is divided by 5, we get a remainder of 3. What will be the remainder if the number is divided by 65 ?
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                        View Hint View Answer Discuss in Forum Let the least number be x.  Correct Option: DLet the least number be x.  
 y = 5 × 1 + 3 = 8
 x = 13 × 8 + 1 = 105
 On dividing 105 by 65,
 ⇒ 105 = ( 65 × 1 ) + 40
 Hence required remainder = 40
-  In a question on division, the divisor is 7 times the quotient and 3 times the remainder. If the remainder is 28, then the dividend is
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                        View Hint View Answer Discuss in Forum Given , Remainder = 28 
 Let the quotient be Q and the remainder be R. Then
 According to question ,
 Divisor = 7 Q = 3 RCorrect Option: DGiven , Remainder = 28 
 Let the quotient be Q and the remainder be R. Then
 According to question ,
 Divisor = 7 Q = 3 R∴ Q = 3 R = 3 × 28 = 12 7 7 
 ⇒ Quotient = 12
 ∴ Divisor = 7 Q = 7 × 12 = 84
 ∴ Dividend = Divisor × Quotient + Remainder = 84 × 12 + 28 = 1008 + 28 = 1036
 Hence the dividend is 1036.
-  A number consists of two digits. If the number formed by interchanging the digits is added to the original number, the resulting number (i.e. the sum) must be divisible by
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                        View Hint View Answer Discuss in Forum Let the number be 10a + b . 
 After interchanging the digits, the number obtained = 10b + a.Correct Option: ALet the number be 10a + b . 
 After interchanging the digits, the number obtained = 10b + a.
 According to the question,
 Resulting number = 10a + b + 10b + a
 Resulting number = 11a + 11b
 Resulting number = 11 (a + b)
 which is exactly divisible by 11.
-  If two numbers are each divided by the same divisor, the remainders are respectively 3 and 4. If the sum of the two numbers be divided by the same divisor, the remainder is 2. The divisor is
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                        View Hint View Answer Discuss in Forum Let two numbers are a and b and the divisor is d . 
 According to question ,∴ R1 = a = 3 d ∴ R2 = b = 4 d 
 Correct Option: CLet two numbers are a and b and the divisor is d . 
 According to question ,∴ R1 = a = 3 d ∴ R2 = b = 4 d Now , R = 3 + 4 = 3 + 4 = 2 d d 
 ⇒ 7 - 2 = 5 is divisible by d .
 Required divisor = 5 { ∴ d > 4 }
 
-  (719 + 2) is divided by 6, the remainder is :
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                        View Hint View Answer Discuss in Forum Using the Binomial expansion , we have 
 (x + 1)n = xn + nc1 xn–1 +
 nc2 xn– 2 + ..... + ncn–1 x +1
 Here, each term except the last term contains x. Obviously, each term except the last term is exactly divisible by x.Correct Option: BUsing the Binomial expansion , we have 
 (x + 1)n = xn + nc1 xn–1 +
 nc2 xn– 2 + ..... + ncn–1 x +1
 Here, each term except the last term contains x. Obviously, each term except the last term is exactly divisible by x.
 Following the same logic,
 ∴ 719 = (6 + 1)19 has each term except last term divisible by 6.
 Hence, 719 + 2 when divided by 6 leaves remainder
 ⇒ 719 + 2 = 1 + 2 = 3
 Hence the remainder is 3.
 
	