What is the HCF of 5, 15 and 20?
The highest common factor of 5, 15 and 20 is the largest possible number which divides 5, 15 and 20 exactly.
Answer: HCF of 5, 15 and 20 is 5.
Let's find the HCF of 5, 15 and 20 by two methods.
Explanation
Method 1: HCF of 5, 15 and 20 by Prime Factorisation Method
 Prime Factorisation of 5: 5
 Prime Factorisation of 15: 3 × 5
 Prime Factorisation of 20: 2 × 2 × 5
Common Factor of 5, 15, and 20 is 5
Hence, the highest common factor of 5, 15 and 20 is 5.
Method 2: HCF of 5, 15 and 20 by Long Division
Follow the steps mentioned below to find the HCF (5, 15, 20) by long division:

Step 1: First take the largest number 20 as a dividend and the smallest number 5 as the divisor, to get common factor 5.

Step 2: Now take the remaining number 15 as dividend and common factor 5 as the divisor.

Step 3: Continue till you get the remainder as 0 and HCF of 5, 15 and 20 is the last divisor obtained.