277 LearnersLast updated on May 26th, 2025
LCM of 4 and 5
LCM is a common multiple, the smallest value between the numbers 4 and 5. 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 4 and 5?
The LCM of 4 and 5 is 20. We can find the LCM using the Listing multiples method, the prime factorization method and the long division method. These are explained below.
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LCM of 4 and 5 using the Listing Multiples Method
Step 1: Write down the multiples of the numbers. Don’t stop too early.
— Multiples of 4 = 4,8,12,16,20…
— Multiples of 5 = 5,10,15,20,…
Step 2: Find the smallest number common between the written multiples of 3 and 8
— The smallest common multiple is 20.
Thus, LCM(4,5) = 20
LCM of 4 and 5 using the Prime Factorization Method
Step 1 — factorize the numbers into its prime factors
4 = 2×2
5= 5×1
Step 2 — find the highest powers of the factors of 4 and 5
Step 3 — Multiply the highest powers
LCM(4,5) = 20
LCM of 4 and 5 using the Division Method
- Write the numbers 4,5 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(4,5) = 20
Common Mistakes and how to avoid them while finding the LCM of 4 and 5
Listed here are a few mistakes that one can commit when trying to find the LCM of the numbers 4 and 5. Try to avoid them.
Mistake 1
Listing incorrect multiples
if the LCM of given numbers is 20, double-check that the number appears on the list of both 4 and 5.
Mistake 2
Prime factorization errors
check if the numbers are prime factored correctly. For example, we may accidentally write 4 = 2×2×3 instead of 4= 2×2.
Mistake 3
Thinking product is the LCM
One may think the product of the numbers is the LCM of the numbers. This is only true in case of co-prime numbers.
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LCM of 4 and 5 Examples
Problem 1
The LCM of 4 and x is 20, find x.
LCM(4,x) = 20
Factors of 4 = 22
Explanation
The LCM of 4,x is 20. The prime factorization of 20 → 22×5, 4 already carries the factor of 22, hence x= 5.
Problem 2
A company has meetings every 4 days and 5 days. If both the conference rooms are booked today, when will they next be booked together ?
LCM(4,5) = 20
Explanation
The conference rooms will be booked on the same day in 20 days again, as the LCM of 4 and 5 is 20, which is the smallest time interval between the digits.
Problem 3
a=4,b=5, verify the relationship between the GCF and LCM of the numbers.
We can verify the relationship using LCM (a,b)×GCF(a,b) = a×b
LCM (4,5) = 20
GCF (4,5) = 1
20×1 = 4×5
20=20
Explanation
Both sides are equal, the formula holds good. The above is how we verify the validity of the LCM and GCF obtained.
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FAQs on LCM of 4 and 5
1. What is the LCM of 4,5 and 1 ?
2. What are the factors of 4 and 5?
3.What is the LCM of 4,5 and 7 ?
4.What are the common factors of 4 and 5?
5.How can children in United Kingdom use numbers in everyday life to understand LCM of 4 and 5?
6.What are some fun ways kids in United Kingdom can practice LCM of 4 and 5 with numbers?
7.What role do numbers and LCM of 4 and 5 play in helping children in United Kingdom develop problem-solving skills?
8.How can families in United Kingdom create number-rich environments to improve LCM of 4 and 5 skills?
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Important glossaries for the LCM of 4 and 5
- 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.
