148 LearnersLast updated on May 26th, 2025
LCM of 20 and 28
The smallest integer that divides the numbers with no numbers left behind is the LCM of 20 and 28. Did you know? We apply LCM unknowingly in everyday situations like setting alarms and to synchronize traffic lights and when making music. In this article, let’s now learn to find LCMs of 20 and 28.
What is LCM of 20 and 28
We can find the LCM using the listing multiples method, prime factorization method and the long division method. These methods are explained here, apply a method that fits your understanding well.
LCM of 20 and 28 using listing multiples method
List the multiples of each of the numbers;
20 = 20,40,60,80,100,120,140,…
28 =28,56,84,112,140,…
Find the smallest number in both the lists
LCM (20,28) = 140
LCM of 20 and 28 using prime factorization method
Prime factorize the numbers
20 = 2×2×5
28= 2×2×7
find the highest powers
2,2,5,7
Multiply the highest powers of the numbers
LCM(20,28) = 140
LCM of 20 and 28 using division method
- Write the numbers in a row
- Divide them with a common prime factor
- Carry forward numbers that are left undivided
- Continue dividing until the remainder is ‘1’
- Multiply the divisors to find the LCM
- LCM (20,28)= 140
Common mistakes and how to avoid them while finding the LCM of 20 and 28
Listed here are a few mistakes children may make when trying to find the LCM due to confusion or due to unclear understanding. Be mindful, understand, learn and avoid!
Mistake 1
Duplicating or skipping a factor
A factor may be missed when we prime factorize a number. Writing the prime factorization of 20 may be written as 2×5×5 instead of 2×2×5 accidentally.
LCM of 20 and 28 Examples
Problem 1
The LCM of 20 and 28 is what percentage of their product?
LCM(20,28)=140
Product of 20 and 28: 20×28=560
Percentage = LCM/Product×100
140/560×100 =25%
Explanation
The LCM is 25% of the product of the numbers.
Problem 2
The LCM of two numbers is 140, and one of the numbers is 28. If the LCM is 70% of the product of the two numbers, find the other number.
Let the other number be x
Given: LCM/28×x=0.7
140=0.7×28×x140 = 0.7×28×x
x=140/0.7×28 =7
Explanation
7 is the other number.
Problem 3
Verify the relationship LCM (20,28)×GCF(20,28)=20×28.
LCM(20,28)=140
GCF(20,28)=4 (Common prime factorization: 22)
Left-hand side: 140×4=560
Right-hand side: 20×28=560
Explanation
Since both sides are equal, the relationship holds true.
FAQs on the LCM of 20 and 28
1. What is the GCF of 20 and 28?
2.What is the LCM of 20,28 and 36 ?
3.What is the LCM of 20,24 and 28?
4.What is the LCM of 20 and 18?
5.What is the LCM of 20 and 27?
6.How can children in India use numbers in everyday life to understand LCM of 20 and 28 ?
7.What are some fun ways kids in India can practice LCM of 20 and 28 with numbers?
8.What role do numbers and LCM of 20 and 28 play in helping children in India develop problem-solving skills?
9.How can families in India create number-rich environments to improve LCM of 20 and 28 skills?
Important glossaries for LCM of 20 and 28
- Multiple: the result after multiplication of a number and an integer. To explain, 20×5 =100; 100 is a multiple of 20.
- Prime Factor: A number with only two factors, 1 and the number. For example,7, its factors are only 1 and 7 and the number when divided by any other integer will leave a remainder behind.
- Prime Factorization: breaking a number down into its prime factors. For example, 20 is written as the product of 2×2×5.
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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
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