Product of two co-prime numbers is 221. Then their LCM is:

To find the LCM (Least Common Multiple) of two numbers, we need to understand what co-prime numbers are and how to calculate the LCM.

Co-prime Numbers:
Co-prime numbers are two numbers that have no common factors other than 1. In other words, their greatest common divisor (GCD) is 1. For example, 3 and 5 are co-prime numbers because their only common factor is 1.

Finding the LCM:
To find the LCM of two numbers, we can use the formula:
LCM(a, b) = (a * b) / GCD(a, b)

Given:
Product of two co-prime numbers is 221.

Step 1: Finding the Factors of 221:
To find the factors of 221, we can divide it by numbers starting from 1 and going up to the square root of 221 (approximately 14.87). If a number divides 221 without leaving a remainder, it is a factor of 221.

Factors of 221:
1, 13, 17, 221

Step 2: Identifying the Co-prime Factors:
Since the given numbers are co-prime, their only common factor is 1. Therefore, the factors we need to consider are 1 and 221.

Co-prime factors of 221:
1, 221

Step 3: Calculating the LCM:
Using the formula LCM(a, b) = (a * b) / GCD(a, b), we can calculate the LCM of the co-prime factors.

LCM(1, 221) = (1 * 221) / GCD(1, 221)

Since the GCD of two co-prime numbers is always 1, the LCM can be calculated as:

LCM(1, 221) = (1 * 221) / 1 = 221

Therefore, the LCM of the two co-prime numbers is 221.

Conclusion:
The correct answer is option 'A' (221). The LCM of two co-prime numbers is equal to their product, which in this case is 221.