HCF of 4 and 20

HCF of 4 and 20 is 4. The Highest Common Factor (HCF) is defined as the largest number, which is a factor of two or more numbers. To find the HCF of numbers, the most frequently used methods are prime factorisation, long division method and listing common factors. The article HCF is well-structured by BYJU’S experts to help students in their effective learning of the HCF concept. Students can make use of this article to get their doubts cleared based on the HCF concept instantly. Learn the simple process of how to calculate the Highest Common Factor of 4 and 20 with the help of solved examples and FAQs in this article.

What is HCF of 4 and 20?

The Highest Common Factor of 4 and 20 is 4. The common factors of 4 and 20 are 1, 2 and 4.

Therefore the number 4 is the highest number that divides both 4 and 20 exactly without leaving any remainder.

How to Find HCF of 4 and 20?

The following three methods are used to find the HCF of 4 and 20:

• Prime Factorisation
• Long Division method
• Listing common factors

HCF of 4 and 20 by Prime Factorisation Method

In the prime factorisation method, to determine the HCF of numbers, we write the given numbers as the product of prime factors. Thus the given numbers 4 and 20 can be written as;

4 = 2 × 2

20 = 2 × 2 × 5

Common prime factors of 4 and 20 are 2 and 2.

Therefore,

HCF (4, 20) = 2 × 2 = 4

HCF of 4 and 20 by Long Division Method

In the long division method, we go through the following steps to determine the HCF of 4 and 20

Step 1: We divide the largest number by the smallest number from the given two numbers.

Step 2: Now, check the remainder. If it is not zero, then make it a new divisor and write the previous divisor as the new dividend. Then perform the division.

Step 3: Repeat this process until we get the remainder equal to zero. The last divisor will be considered as the HCF of the given two numbers.

The HCF of 4 and 20 by the long division method is shown below;

HCF (4, 20) = 4

HCF of 4 and 20 by Listing the Factors

In this method, we need to express all the factors of 4 and 20 to find their HCF. The factors of 4 and 20 are mentioned below;

Factors of 4: 1, 2, 4

Factors of 20: 1, 2, 4, 5, 10, 20

Hence, HCF (4, 20) = 4

Related Articles

• HCF of Two Numbers
• GCF
• HCF and LCM
• GCF Calculator
• HCF
• Highest Common Factor

Video Lesson on Properties of HCF and LCM

Solved Examples

1. What is the highest number that divides both 4 and 20 exactly?

Solution: The highest number that divides both 4 and 20 exactly is their Highest Common Factor (HCF). To determine the HCF, let us list the factors of 4 and 20

Factors of 4: 1, 2, 4

Factors of 20: 1, 2, 4, 5, 10, 20

Clearly, 4 is the HCF of 4 and 20. Therefore, the highest number that divides both 4 and 20 exactly is 4. 

2. What is the LCM if the product of two numbers is 80 and their HCF is 4?

Solution: Given

HCF = 4

Product of numbers = 80

We know that

LCM × HCF = Product of numbers

LCM = Product of numbers/HCF

LCM = 80/4

LCM = 20

Hence the LCM is 20.