LCM and HCF
-  The smallest number, which when increased by 5 is divisible by each of 24,32, 36 and 564, is
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                        View Hint View Answer Discuss in Forum Required number = (LCM of 24, 32, 36 and 54) – 5 
 Now,LCM of 24, 32, 36 and 54 
 LCM = 2 × 2 × 2 × 3 × 3 × 3 × 4 = 864Correct Option: BRequired number = (LCM of 24, 32, 36 and 54) – 5 
 Now,LCM of 24, 32, 36 and 54 
 LCM = 2 × 2 × 2 × 3 × 3 × 3 × 4 = 864
 ∴ Required number = 864 – 5 = 859
-  The number nearest to 43582 divisible by each of 25, 50 and 75 is :
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                        View Hint View Answer Discuss in Forum LCM of 25, 50 and 75 = 150 
 On dividing 43582 by 150, remainder = 82 
 ∴ Required number = 43582 + (150 – 82)Correct Option: BLCM of 25, 50 and 75 = 150 
 On dividing 43582 by 150, remainder = 82 
 ∴ Required number = 43582 + (150 – 82) = 43650
-  The least number, which is a perfect square and is divisible by each of the numbers 16, 20 and 24, is
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                        View Hint View Answer Discuss in Forum The smallest number divisible by 16, 20 and 24 
 = LCM of 16, 20 and 24 
 ∴ LCM = 2 × 2 × 2 × 2 × 5 × 3
 LCM = 22 × 22 × 5 × 3Correct Option: BThe smallest number divisible by 16, 20 and 24 
 = LCM of 16, 20 and 24 
 ∴ LCM = 2 × 2 × 2 × 2 × 5 × 3
 LCM = 22 × 22 × 5 × 3
 ∴ Required complete square number = 22 × 22 × 52 × 32 = 3600
-  The largest 4-digit number exactly divisible by each of 12, 15, 18 and 27 is
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                        View Hint View Answer Discuss in Forum As we know that Greatest n digit number which when divided by three numbers p,q,r leaves no remainder will be Required Number = (n – digit greatest number) – R , R is the remainder obtained on dividing greatest n digit number by L.C.M of p.q,r. 
 The largest number of 4-digits is 9999. L.C.M. of divisors 
 LCM = 2 × 2 × 3 × 3 × 3 × 5 = 540Correct Option: BAs we know that Greatest n digit number which when divided by three numbers p,q,r leaves no remainder will be Required Number = (n – digit greatest number) – R , R is the remainder obtained on dividing greatest n digit number by L.C.M of p.q,r. 
 The largest number of 4-digits is 9999. L.C.M. of divisors 
 LCM = 2 × 2 × 3 × 3 × 3 × 5 = 540
 Divide 9999 by 540, now we get 279 as remainder.
 9999 – 279 = 9720
 Hence, 9720 is the largest 4-digit number exactly divisible by each of 12, 15, 18 and 27.
-  From a point on a circular track 5 km long A, B and C started running in the same direction at the same time with speed of 21/2 km per hour, 3 km per hour and 2 km per hour respectively. Then on the starting point all three will meet again after
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                        View Hint View Answer Discuss in Forum A makes one complete round of the circular track in 5 = 2 hours, 5 2 B in 5 hours and C in 5 hours. 3 2 
 That is after 2 hours A is at the starting point,B after 5 hours and C after 5 hours. 3 2 Hence the required time = LCM of 2, 5 and 5 hours 3 2 Required time = LCM of 2, 5, 5 HCF of 1 , 3 , 2 
 Correct Option: CA makes one complete round of the circular track in 5 = 2 hours, 5 2 B in 5 hours and C in 5 hours. 3 2 
 That is after 2 hours A is at the starting point,B after 5 hours and C after 5 hours. 3 2 Hence the required time = LCM of 2, 5 and 5 hours 3 2 Required time = LCM of 2, 5, 5 HCF of 1 , 3 , 2 Required time = 10 = 10 hours. 1 
 
	