Short Answer 
To find the Highest Common Factor (HCF) of two or more integers, start by identifying the numbers and listing their factors. For example, the factors of 20 are 1, 2, 4, 5, 10, and 20, while the factors of 30 are 1, 2, 3, 5, 6, 10, 15, and 30; the common factors are 1, 2, 5, and 10, with the HCF being 10.
Identify the Scenario
To find the Highest Common Factor (HCF), start by identifying the numbers involved. This could be two or more integers for which you aim to find the largest number that divides them without leaving a remainder. For example, consider the numbers 20 and 30.
List the Factors
Next, create a list of factors for each number. A factor is a number that can divide the input number evenly. For the chosen numbers, the factors would be:
- Factors of 20: 1, 2, 4, 5, 10, 20
- Factors of 30: 1, 2, 3, 5, 6, 10, 15, 30
Identify the common factors between these lists.
Determine the Highest Common Factor
Finally, examine the list of common factors to find out which one is the greatest. In our example of 20 and 30, the common factors are 1, 2, 5, and 10. The Highest Common Factor is therefore the largest number from this list, which is 10.