Why do we use the process of Prime Factorisation for obtaining LCM & HCF of some numbers?๐ค
Prime factorization is a powerful tool for finding the Highest Common Factor (HCF) and Least Common Multiple (LCM) of numbers because it breaks them down into their most basic building blocks: prime numbers. Here's why it works so well:
1. Uniqueness of Prime Numbers:
- Any whole number can be expressed as a product of prime numbers (and 1), in a single way. This is called the Fundamental Theorem of Arithmetic.
- Prime numbers are the building blocks of whole numbers – they cannot be further broken down into smaller whole numbers.
2. HCF and LCM in terms of Prime Factors:
- HCF: The HCF represents the greatest number that is a factor of both original numbers. In terms of prime factors, the HCF is the product of the highest powers of common prime factors present in both numbers.
- LCM: The LCM represents the smallest number that is a multiple of both original numbers. In terms of prime factors, the LCM is the product of the highest powers of all the prime factors present in either number.
Benefits of using Prime Factorization:
- Simplifies Calculations: Breaking down numbers into their prime factors allows us to focus on the individual prime numbers instead of manipulating large whole numbers. This can simplify calculations, especially for larger numbers.
- Identifies Common Factors: By looking at the prime factorization of both numbers, it's easy to identify the common prime factors and their corresponding powers. This helps determine the HCF directly.
- Efficient LCM Calculation: The LCM involves finding the highest power of each prime factor present in either number. Prime factorization makes it easy to identify these highest powers.
Example:
Let's find the HCF and LCM of 12 and 18 using prime factorization:
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Prime Factorization:
- 12 = 2 x 2 x 3
- 18 = 2 x 3 x 3
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HCF:
- Highest powers of common prime factors: 2 x 3 (both numbers have 2 raised to the power of 1 and 3 raised to the power of 1)
- HCF = 2 x 3 = 6
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LCM:
- Highest powers of all prime factors: 2 x 2 x 3 x 3 (take the highest power of each prime factor that appears in either number)
- LCM = 2 x 2 x 3 x 3 = 36
In conclusion:
Prime factorization provides a systematic and efficient way to find the HCF and LCM by focusing on the fundamental building blocks of numbers – prime numbers. It simplifies calculations, makes identifying common factors easier, and leads to a clear understanding of how these concepts relate to the underlying structure of numbers.
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