Question 2
Find the LCM and HCF of the following pairs of integers and verify that LCM × HCF = product of the two numbers.
(i) 26 and 91 (ii) 510 and 92 (iii) 336 and 54
We will use prime factorization to find the LCM and HCF. Then we will verify the product rule.
Step 1 — Find LCM and HCF for 26 and 91
Let's find the prime factors.
We find common prime factors. We take the lowest power.
We find all prime factors. We take the highest power.
Let's multiply the given numbers.
Let's multiply the HCF and LCM.
Both results are the same. The property is verified.

Step 2 — Find LCM and HCF for 510 and 92
Let's find the prime factors.
We find common prime factors. We take the lowest power.
We find all prime factors. We take the highest power.
Let's multiply the given numbers.
Let's multiply the HCF and LCM.
Both results are the same. The property is verified.
Step 3 — Find LCM and HCF for 336 and 54
Let's find the prime factors.
We find common prime factors. We take the lowest power.
We find all prime factors. We take the highest power.
Let's multiply the given numbers.
Let's multiply the HCF and LCM.
Both results are the same. The property is verified.
Answer
(i) HCF = 13, LCM = 182. Product of numbers = 2366, HCF × LCM = 2366. Verified. (ii) HCF = 2, LCM = 23460. Product of numbers = 46920, HCF × LCM = 46920. Verified. (iii) HCF = 6, LCM = 3024. Product of numbers = 18144, HCF × LCM = 18144. Verified.
More questions in Exercise 1.1
Express each number as a product of its prime factors:
(i) 140 (ii) 156 (iii) 3825 (iv) 5005 (v) 7429
Find the LCM and HCF of the following pairs of integers and verify that LCM × HCF = product of the two numbers.
(i) 26 and 91 (ii) 510 and 92 (iii) 336 and 54
Find the LCM and HCF of the following integers by applying the prime factorisation method.
(i) 12, 15 and 21 (ii) 17, 23 and 29 (iii) 8, 9 and 25
Given that HCF (306, 657) = 9, find LCM (306, 657).
Check whether can end with the digit 0 for any natural number .
Explain why and are composite numbers.
There is a circular path around a sports field. Sonia takes 18 minutes to drive one round of the field, while Ravi takes 12 minutes for the same. Suppose they both start at the same point and at the same time, and go in the same direction. After how many minutes will they meet again at the starting point?