Finding the Largest Prime Factor of a Number

In mathematics, prime factors are the building blocks of numbers. They are important in understanding the structure and properties of numbers. In this guide, we’ll explore how to find the largest prime factor of a given number. This step-by-step tutorial will help you grasp the process easily and effectively.

Understanding Prime Factors

Before diving into the main topic, let’s briefly understand prime factors. A prime number is a number greater than 1 that has only two distinct positive divisors: 1 and itself. A prime factor, on the other hand, is a prime number that divides a given number exactly, leaving no remainder.

For example, the prime factors of 12 are 2 and 3, as 12 = 2 x 2 x 3. Now, let’s find the largest prime factor of a given number.

Step-by-Step Guide to Finding the Largest Prime Factor

Step 1: Find the Smallest Prime Factor

The first step in finding the largest prime factor of a number is to find the smallest prime factor. Start by checking if the number is divisible by the smallest prime number, which is 2. If it is divisible by 2, then the smallest prime factor is 2. If not, move on to the next smallest prime number, which is 3, and continue checking until you find a prime number that divides the given number exactly.

Step 2: Divide the Number by the Smallest Prime Factor

Once you have found the smallest prime factor, divide the given number by this factor. The result will be a new, smaller number. This is the quotient.

Step 3: Repeat Steps 1 and 2 for the Quotient

Now, repeat steps 1 and 2 for the quotient obtained in step 2. Find the smallest prime factor of the quotient and divide the quotient by this factor. Keep repeating these steps until the quotient becomes a prime number.

Step 4: Identify the Largest Prime Factor

The largest prime factor is the prime number obtained in step 3 when the quotient becomes a prime number. This is the largest prime factor of the given number.

Example: Finding the Largest Prime Factor of 84

Now, let’s apply the steps mentioned above to find the largest prime factor of the number 84.

1. Find the smallest prime factor: The smallest prime factor of 84 is 2, as 84 is divisible by 2.
2. Divide the number by the smallest prime factor: 84 ÷ 2 = 42
3. Repeat steps 1 and 2 for the quotient: The smallest prime factor of 42 is 2. 42 ÷ 2 = 21
4. Repeat steps 1 and 2 for the new quotient: The smallest prime factor of 21 is 3. 21 ÷ 3 = 7
5. The quotient is now a prime number (7). Hence, the largest prime factor of 84 is 7.

Conclusion

Finding the largest prime factor of a number is a crucial skill in mathematics. By following the step-by-step guide outlined in this tutorial, you can quickly and easily determine the largest prime factor of any number.