LCM and HCF

LCM Definition

In mathematics, the Least Common Multiple, abbreviated as LCM, is a fundamental concept. The LCM of two numbers, such as a and b, is represented as LCM(a, b). It is defined as the smallest positive integer that is divisible by both a and b.

For instance, consider the positive integers 4 and 6:

  • The multiples of 4 are: 4, 8, 12, 16, 20, 24, and so on.
  • The multiples of 6 are: 6, 12, 18, 24, and so forth.

The common multiples of 4 and 6 include: 12, 24, 36, 48, and so on. Among these, the smallest common multiple is 12. Hence, the LCM of 4 and 6 is 12.

Now, let's determine the LCM of 24 and 15:

  • The multiples of 24 are: 24, 48, 72, 96, 120, and so on.
  • The multiples of 15 are: 15, 30, 45, 60, 75, 90, 105, 120, and so forth.

The common multiples of 24 and 15 include: 120, 240, 360, etc. Among these, the smallest common multiple is 120. Therefore, the LCM of 24 and 15 is 120.

Also Check: Full Form of HCF

LCM of Two Numbers

Finding the LCM of 8 and 12

Let's try to find the Least Common Multiple (LCM) of two numbers, 8 and 12. We will look at the multiples of these two numbers to determine their LCM.

  • The multiples of 8 are: 8, 16, 24, 32, 40, 48, 56, and so on.
  • The multiples of 12 are: 12, 24, 36, 48, 60, 72, 84, and so forth.

As you can see, the smallest common multiple of the numbers 8 and 12 is 24. Therefore, the LCM of 8 and 12 is 24.

Understanding HCF

In mathematics, HCF stands for Highest Common Factor. The largest positive integer that divides two or more positive integers without leaving a remainder is called the Greatest Common Divisor (GCD) or HCF.

Consider the numbers 8 and 12. The maximum number that can divide both 8 and 12 is 4. Therefore, the HCF of 8 and 12 is 4.

Also Chek: How to find HCF

Example: Finding the HCF of 24 and 36

To find the HCF of 24 and 36, we use prime factorization:

  • 24 = 2 × 2 × 2 × 3
  • 36 = 2 × 2 × 3 × 3

By factoring the numbers, we see that the common factors are 2 × 2 × 3. Therefore, the HCF of 24 and 36 is:

HCF(24, 36) = 2 × 2 × 3 = 12

HCF and LCM Formula

Combining HCF and LCM

The Highest Common Factor (HCF) and the Least Common Multiple (LCM) are related through a fundamental formula in mathematics. This relationship is given by the following formula:

A × B = HCF(A, B) × LCM(A, B)

Here, A and B are two numbers, HCF(A, B) is the Highest Common Factor of A and B, and LCM(A, B) is the Least Common Multiple of A and B.

Formulas in Terms of HCF and LCM

Using the relationship between HCF and LCM, we can derive the following formulas:

Finding HCF

The HCF of two numbers can be calculated as:

HCF of Two Numbers = (Product of Two Numbers) / (LCM of Two Numbers)

Finding LCM

The LCM of two numbers can be calculated as:

LCM of Two Numbers = (Product of Two Numbers) / (HCF of Two Numbers)

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Frequently Asked Questions on LCM and HCF

The rule for finding the Least Common Multiple (LCM) and Highest Common Factor (HCF) of two or more numbers is:

  1. Write each number as the product of its prime factors
  2. For LCM, multiply each prime factor by the highest power it occurs in any number
  3. For HCF, multiply the common prime factors with the lowest power they occur

The rule for finding the Highest Common Factor (HCF) of two or more numbers is:

  1. Write each number as the product of its prime factors
  2. List the common prime factors
  3. Multiply the common factors using the lowest power they occur

To find the Least Common Multiple (LCM) quickly, use the prime factorization method:

  1. Write each number as the product of its prime factors
  2. Multiply each prime factor by the highest power it occurs in any number

To find the Highest Common Factor (HCF) quickly, use the prime factorization method:

  1. Write each number as the product of its prime factors
  2. List the common prime factors
  3. Multiply the common factors using the lowest power they occur

The list method to find the Highest Common Factor (HCF) involves:

  1. List the factors of each number
  2. Find the common factors between the numbers
  3. The largest common factor is the HCF