## Steps to calculate GCD/HCF using Common Prime Factors Method

In programming and other mathematical questions *GCD of Two numbers* is calculated most of the time.

This is also called highest common factor calculator. Finding the greatest common factor calculator can get input of multiple numbers separated by space.

Out of multiple ways for calculating Greatest Common Divisor or **Highest Common Factor**,
one method is used very frequently. This technique is also part of curriculum in some institutes. This method
involves a series of steps from finding prime factors to calculated *GCD*. These steps are as below.
**GCD in discrete mathematics** involves computation for multiple numbers.

- First of all find prime factors of each given number.
- Write these factors in some sorted order, can say that align these factors so that we can highlight common factors easily.
- Circle or underline common factors from each number.
*Common factors are numbers that appear as prime factor of each number.* - In the last step multiply each common factor.
- The resultant multiplication is the GCD/HCF of provided numbers.

In case that there is not a single prime factor is common from all numbers then the GCD will be 1.

### Example

### GCD Practice Questions

Some of the important questions that can be solved as practice are as.

- Calculate GCD of 12, 45, 66
- Find the HCF of numbers 56, 44, 18, 90
- What is the GCD or HCF of 34, 5, 16, 24 and 88
- Calculate HCF using common prime factors of 55, 88, 77 and 21
- Write down steps of calculating Greatest Common Divisor
- Find GCD of 56 and 45
- Use prime factor technique for finding GCD of 28, 16, 42, 200 and 150
- Find the HCF of the following numbers 34, 16, 30, 22