LCM and HCF
-  How many numbers are there between 4000 and 6000 which are exactly divisible by 32, 40, 48 and 60?
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                        View Hint View Answer Discuss in Forum LCM of 32, 40, 48 and 60 = 480 
 The number divisible by 480 between 4000 and 6000 are 4320, 4800, 5280 and 5760.Correct Option: CLCM of 32, 40, 48 and 60 = 480 
 The number divisible by 480 between 4000 and 6000 are 4320, 4800, 5280 and 5760.
 Hence, required number of numbers are 4.
-  The sum of two numbers is 1056 and their HCF is 66, Find the Number of such pairs.
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                        View Hint View Answer Discuss in Forum Let the numbers be 66a and 66b, where a and b are co-primes. 
 According to the question,
 66a + 66b = 1056
 ⇒ 66(a + b) = 1056
 ⇒ (a + b) = 1056/66 = 16
 ∴ Possible values of a and b are
 (a = 1, b = 15), (a = 3, b = 13).
 (a = 5, b = 11 ), (a = 7, b = 9)Correct Option: CLet the numbers be 66a and 66b, where a and b are co-primes. 
 According to the question,
 66a + 66b = 1056
 ⇒ 66(a + b) = 1056
 ⇒ (a + b) = 1056/66 = 16
 ∴ Possible values of a and b are
 (a = 1, b = 15), (a = 3, b = 13).
 (a = 5, b = 11 ), (a = 7, b = 9)
 ∴ Numbers are
 (66 x 1, 66 x 15), (66 x 3, 66 x 13),
 (66 x 5, 66 x 11), (66 x 7, 66 x 9).
 ∴ Possible number of pairs = 4
-  The HCF and LCM of two natural numbers are 12 and 72, respectively. What is the difference between the two numbers, if one of the number is 24?
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                        View Hint View Answer Discuss in Forum Second number = (LCM x HCF) / first number Correct Option: ASecond number = (LCM x HCF) / first number 
 = (72 x 12)/ 24 = 36
 Difference between the two numbers
 = 36 - 24 = 12
-  The ratio of two numbers is 3 : 4 and their HCF is 4. What will be their LCM?
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                        View Hint View Answer Discuss in Forum According to the question, 
 1st number = 3M, 2nd number = 4M
 where, M = HCF
 But given, M = 4
 We know that,
 LCM = Product of two numbers / HCFCorrect Option: DAccording to the question, 
 1st number = 3M, 2nd number = 4M
 where, M = HCF
 But given, M = 4
 We know that,
 LCM = Product of two numbers / HCF
 = (3M x 4M) / M
 LCM = 12M = 12 x 4 = 48
-  For any integer n, What is HCF (22n + 7, 33n + 10) equal to?
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                        View Hint View Answer Discuss in Forum HCF of (22n + 7, 33n + 10) is always 1. 
 lllustraction
 For n = 1, HCF(29, 43) ⇒ HCF = 1
 For n = 2, HCF(51, 76) ⇒ HCF = 1
 For n = 3, HCF(73, 109) ⇒ HCF = 1Correct Option: BHCF of (22n + 7, 33n + 10) is always 1. 
 lllustraction
 For n = 1, HCF(29, 43) ⇒ HCF = 1
 For n = 2, HCF(51, 76) ⇒ HCF = 1
 For n = 3, HCF(73, 109) ⇒ HCF = 1
 
	