LCM of 20 and 28 is 72. In Maths, the LCM of any two numbers is the value which is evenly divisible by the given two numbers. LCM of 20 and 28 is the smallest number among all common multiples of 20 and 28. The first few multiples of 20 and 28 are (20, 40, 60, 80, 100, 120, . . . ) and (28, 56, 84, 112, 140, . . . ) respectively. The LCM can be found easily by using various methods like prime factorisation, division and by listing the multiples.
Also read: Least common multiple
What is LCM of 20 and 28?
The answer to this question is 140. The LCM of 20 and 28 using various methods is shown in this article for your reference. The LCM of two non-zero integers, 20 and 28, is the smallest positive integer 140 which is divisible by both 20 and 28 with no remainder.
How to Find LCM of 20 and 28?
LCM of 20 and 28 can be found using three methods:
- Prime Factorisation
- Division method
- Listing the multiples
LCM of 20 and 28 Using Prime Factorisation Method
The prime factorisation of 20 and 28, respectively, is given by:
(2 × 2 × 5) = 22 × 51 and (2 × 2 × 7) = 22 × 71
LCM (24, 36) = 140
LCM of 20 and 28 Using Division Method
We’ll divide the numbers (20, 28) by their prime factors to get the LCM of 20 and 28 using the division method (preferably common). The LCM of 20 and 28 is calculated by multiplying these divisors.
| 2 | 24 | 36 |
| 2 | 20 | 28 |
| 2 | 10 | 14 |
| 5 | 5 | 7 |
| 7 | 1 | 7 |
| x | 1 | 1 |
No further division can be done.
Hence, LCM (20, 28) = 140
LCM of 20 and 28 Using Listing the Multiples
To calculate the LCM of 20 and 28 by listing out the common multiples, list the multiples as shown below
| Multiples of 20 | Multiples of 28 |
| 20 | 28 |
| 40 | 56 |
| 60 | 84 |
| 80 | 112 |
| 100 | 140 |
| 120 | 168 |
| 140 | 196 |
The smallest common multiple of 20 and 28 is 140.
Therefore LCM (20, 28) = 140
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LCM of 20 and 28 Solved Example
Question: The product of two numbers is 560. If their GCD is 4, what is their LCM?
Solution:
Given: GCD = 4
product of numbers = 560
∵ LCM × GCD = product of numbers
⇒ LCM = Product/GCD = 560/4
Therefore, the LCM is 140.
The probable combination for the given case is LCM(20, 28) = 140.
Frequently Asked Questions on LCM of 20 and 28
What is the LCM of 20 and 28?
List the methods used to find the LCM of 20 and 28.
What is the Relation Between GCF and LCM of 20, 28?
If the LCM of 28 and 20 is 140, Find its GCF.
Since the LCM of 28 and 20 = 140
⇒ 140 × GCF(28, 20) = 560
Therefore, the greatest common factor = 560/140 = 4.
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