LCM of 5 and 20
2026-02-28 23:33 Diff
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Last updated on August 5, 2025

LCM is a common multiple, the smallest value between the numbers 5 and 20. Did you know? We apply LCM unknowingly in everyday situations like setting alarms and to synchronize traffic lights and when making music.

What is the LCM of 5 and 20?

LCM of 5 and 20 Using Listing the Multiples

Step 1: Write down the multiples of the numbers. Don’t stop too early.


Multiples of 5 = 5,10,15,20,25,…


Multiples of 20 = 20,40,60,80…


Step 2: Find the smallest number common between the written multiples of 5 and 20


The smallest common multiple is 20


Thus, LCM(5,20) = 20
 

LCM of 5 and 20 Using Prime Factorization

Step 1: factorize the numbers into its prime factors 


 5 = 5


20 = 2×2×5  


Step 2:  find the highest powers of the factors of 5 and 20


Step 3: Multiply the highest powers 


LCM(5,20) = 20

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LCM of 5 and 20 Using Division Method

  • Write the numbers 5,20 in a row 
  • Divide them by their common prime factors, if there is one
  • Carry forward the numbers that are left undivided by the previously chosen factor
  • Continue dividing until the remainder is ‘1’ 
  • Multiply the divisors to find the LCM
  • LCM(5,20) = 20
     

Common Mistakes and how to avoid them while finding the LCM of 5 and 20

Listed here are a few mistakes that one can commit when trying to find the LCM of the numbers 5 and 20. Try to avoid them. 
 

Problem 1

Callie and Dan meet every 5 days and 20 days, respectively. They meet today, September 1, how many days will it be before they meet again?

Okay, lets begin

 Find the LCM of 5 and 20: LCM (5,20) = 20. 
 

Explanation

They will meet again in 20 days. The LCM of 5 and 20 is the smallest common multiple of the digits. 
 

Well explained 👍

Problem 2

Ascertain the smallest positive integer solution x to the equation given below, using the LCM of 5 and 20. x=0 (mod 5) and x=0 (mod 20)

Okay, lets begin

Find the prime factors of the numbers:
Prime factorization of 5 = 2


Prime factorization of 20 = 2×2×5  

—  Take the highest power of each prime factor:


— 2,2,5


— Multiply the ascertained factors to get the LCM: 


LCM (5,12) = 2×2×5 = 20 


x = 20
 

Explanation

The question asks to find the smallest x that is divisible by both 5 and 20, which essentially is just finding the least common multiple(LCM) of 5 and 20. 

Well explained 👍

Problem 3

If an integer x is divisible by 5 and 20, express x as a multiple of LCM of 5 and 20. Also, find x.

Okay, lets begin

x is divisible by both 5 and 20, so is must be a multiple of the LCM of the numbers. 


LCM that was previously calculated is 20. 


Therefore, x = 20.n, for some integer n. 
 

Explanation

The minimum value of x is ascertained when n=1, so the minimum value of x = 20. 

Well explained 👍

FAQ’s on the LCM of 5 and 20

1.What is the LCM of 5,12 and 15?

60 is the smallest number that appears commonly on the lists of the numbers 5,12 and 15.

LCM (5,12,15) = 60
 

2.What is the HCF of 12 and 15?

HCF of 12 and 15 can be found by listing the factors of the numbers → finding the largest common factor from the list of numbers. 


Factors of 12 = 1,2,3,4,6,12


Factors of 15 = 1,3,5,15 


HCF (12,15) = 3 
 

3.What is the LCM of 15 and 21?

LCM (15,21) = 105 


105 is the smallest number that appears commonly on the lists of the numbers 15 and 21. 
 

4.What is the LCM of 48 and 60?

240 is the smallest number that appears commonly on the lists of the numbers 48 and 60. 


LCM (48,60) = 240
 

5.What is the LCM of 9 and 33?

LCM (9,33)= 99


99 is the smallest number that appears commonly on the lists of the numbers 9 and 33. 
 

Important glossaries on the LCM of 5 and 20

  • Multiple — product of a number and a natural integer 
  • Prime factor — number one gets after prime factorization any given number 
  • Prime factorization — the process of breaking the number into its prime factors. 

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Hiralee Lalitkumar Makwana

About the Author

Hiralee Lalitkumar Makwana has almost two years of teaching experience. She is a number ninja as she loves numbers. Her interest in numbers can be seen in the way she cracks math puzzles and hidden patterns.

Fun Fact

: She loves to read number jokes and games.