HCF and LCM – Railway Maths Part Ⅵ

Total Questions: 50

1. The HCF of two numbers is 20 and their LCM is 400. If one of the numbers is 80, then the other number is: [RRB NTPC 15/02/2021 (Morning)]

Correct Answer: (c) 100

2. Calculate the least perfect square, which is exactly divisible by each of 2, 5, 7, 8 and 10 [RRB NTPC 15/02/2021 (Evening)]

Correct Answer: (d) 19600

3. Calculate the greatest possible length which can be used to measure exactly the length 220cm, 260cm and 300cm. [RRB NTPC 15/02/2021 (Evening)]

Correct Answer: (a) 20 cm

4. Find the least number which when divided by 5 leaves no remainder, when divided by 4 leaves a remainder of 1 but when divided by 6 or 7 leaves a remainder of 5. [RRB NTPC 15/02/2021 (Evening)]

Correct Answer: (c) 425

5. The sum of two numbers is 60, and their difference is 1 / 6 of their sum. Their LCM is: [RRB NTPC 16/02/2021 (Morning)]

Correct Answer: (a) 175

6. A pendulum strikes 2 times in 3 sec, and another pendulum strikes 5 times in 7 sec. If both pendulums start striking at the same time, how many simultaneous strikes will take place in 1 min? [RRB NTPC 16/02/2021 (Evening)]

Correct Answer: (b) 2

7. If the product of two co-primes is 104, then their LCM: [RRB NTPC 17/02/2021 (Morning)]

Correct Answer: (c) 1

8. The product of the LCM and the HCF of two positive numbers is 32 and the difference of the numbers is 4. The sum of the same numbers is. [RRB NTPC 17/02/2021 (Morning)]

Correct Answer: (b) 12

9. The LCM of two prime numbers, a and b (a > b > 1), is 697. The value of a + 2b is. [RRB NTPC 17/02/2021 (Morning)]

Correct Answer: (a) 7 

10. Three positive numbers are in the ratio of 1 : 2 : 5 and their LCM is 120. The HCF of the same numbers is: [RRB NTPC 17/02/2021 (Morning)]

Correct Answer: (c) 12