The HCF of 15, 25 and 30 is 5. The HCF of 15, 25 and 30 is the greatest integer that can divide the given numbers evenly, and that number is 5. HCF stands for Highest Common Factor. It is also known as GCF, Greatest Common Factor or GCD, Greatest Common Divisor. For the given set of numbers, 1 and 5 are the common factors, out of which 5 is the highest common factor. Hence, 5 is the HCF of 15, 25 and 30. The HCF of 3 numbers can be calculated using different methods, which can be referred to below. Also, read the article on HCF and LCM for details.
What is the HCF of 15, 25 and 30?
The Highest Common Factor, also known as the Greatest Common Factor, of 15, 25 and 30 is 5.
How to Find HCF of 15, 25 and 30?
There are three methods to find the HCF of 15, 25 and 30:
- Prime Factorisation
- Long Division method
- Listing common factors
HCF of 15, 25 and 30 by Prime Factorisation Method
In the Prime Factorisation method, the numbers can be expressed as the product of prime numbers. Here, 15, 25 and 30 can be expressed as:
15 = 3 × 5
25 = 5 × 5
30 = 2 × 3 × 5
The only Common Prime Factor is 5.
Therefore, HCF (15, 25 and 30) = 5.
HCF of 15, 25 and 30 by Long Division Method
In the Long division method, the following steps are followed.
- Choose two numbers from the given set of numbers. (Usually, the first two numbers are selected)
- From the chosen numbers, the smallest number becomes the divisor, and the larger number becomes the dividend.
- In the next step, the smaller number becomes the dividend, and the remainder becomes the divisor.
- The above step is followed until the remainder is zero.
- The last divisor would be the HCF.
- The obtained HCF and the third number are taken for a new long division.
- HCF becomes the divisor, and the other number becomes the dividend.
- Long division is continued till the remainder becomes zero.
- The last divisor is the HCF of all three numbers.
HCF of 15, 25 and 30 by long division method is:
Stage 1: Choosing 15 and 25 for the 1st Long Division, the HCF of 15 and 25 is 5.
Stage 2: Choosing HCF and next number for Long Division.
i.e. HCF from the previous Long Division is 5, and left-out number is 30, the HCF is 5.
Division for both stages is shown in the image below.
So, HCF (15, 25 and 30) = 5
HCF of 15, 25 and 30 by Listing Common Factors
By listing all the factors of given numbers, we can identify the Highest/Greatest/Biggest common factor, which is the HCF. Below is the list of factors for 15, 25 and 30:
Factors of 15: 1, 3, 5, 15.
Factors of 25: 1, 5, 25
Factors of 30: 1, 2, 3, 5, 6, 5, 15, 30
Therefore, HCF (15, 25 and 30) = 5
Related Articles
Video Lesson on Properties of HCF and LCM
Solved Examples
1. Find the Greatest number that divides 30, 60 and 90.
The Greatest number that divides 30, 60 and 90 is nothing but the GCF, which is 30.
2. What is the GCF of 18, 6 and 24?
GCF of 18, 6 and 24 is 6.
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