LCM of 28 and 30
420 is the LCM of 28 and 30. The step-by-step solution using prime factors and special division methods is one of the simple methods to easily understand how to find what is the LCM of 28 and 30, provided along with the use cases of mathematics and real-world problems.
what is the lcm of 28 and 30?
lcm (28 30) = (?)
28 => 2 x 2 x 7
30 => 2 x 3 x 5
= 2 x 2 x 7 x 3 x 5
= 420
lcm (28 and 30) = 420
420 is the LCM of 28 and 30.
where,
28 is a positive integer,
30 is a positive integer,
420 is the LCM of 28 and 30,
{2} in {2 x 2 x 7, 2 x 3 x 5} is the common factors of 28 and 30,
{2 x 7 x 3 x 5} in {2 x 2 x 7, 2 x 3 x 5} are the uncommon factors of 28 and 30.
Use in Mathematics: LCM of 28 and 30
The below are some of the mathematical applications where lcm of 28 and 30 can be used:
- to find the least number which is exactly divisible by 28 and 30.
- to find the common denominator for two fractions having 28 and 30 as denominators in the unlike fractions addition or subtraction.
In the context of lcm real world problems, the lcm of 28 and 30 helps to find the exact time when two similar and recurring events with different time schedule happens together at the same time. For example, the real world problems involve lcm in situations to find at what time the bells A and B all toll together, if bell A tolls at 28 seconds and bell B tolls at 30 seconds repeatedly. The answer is that all bells A and B toll together at 420 seconds for the first time, at 840 seconds for the second time, at 1260 seconds for the third time and so on.
Important Notes: 28 and 30 lcm
The below are the important notes to be remembered while solving the lcm of 28 and 30:
- The common prime factors and the remaining prime factors of 28 and 30 should be multiplied to find the least common multiple of 28 and 30, when solving lcm by using prime factors method.
- The results of lcm of 28 and 30, and the lcm of 30 and 28 are identical, it means the order of given numbers in the lcm calculation doesn't affect the results.
How-to: What is the LCM of 28 and 30?
The below solved example with step by step work shows how to find what is the lcm of 28 and 30 by using prime factors method and division method.
Solved example using prime factors method:
What is the LCM of 28 and 30?
step 1
Address the input parameters, values and observe what to be found:
Input parameters and values:
A = 28
B = 30
What to be found:
find the lcm of 28 and 30
step 2 Find the prime factors of 28 and 30:
Prime factors of 28 = 2 x 2 x 7
Prime factors of 30 = 2 x 3 x 5
step 3 Identify the repeated and non-repeated prime factors of 28 and 30:
{2} is the most repeated factor and {2 x 7 x 3 x 5} are the non-repeated factors of 28 and 30.
step 4 Find the product of repeated and non-repeated prime factors of 28 and 30:
= 2 x 2 x 7 x 3 x 5
= 420
lcm(28 and 30) = 420
Hence,
lcm of 28 and 30 is 420
This special division method is one of the easiest ways to understand the entire calculation to find the LCM of 28 and 30.
step 1 Address the input parameters, values and observe what to be found:
Input parameters and values:
Integers: 28 and 30
What to be found:
lcm (28, 30) = ?
step 2 Arrange the given integers in the horizontal form with space or comma separated format:
28 and 30
step 3 Choose the divisor which divides each or most of the given integers (28 and 30), divide each integers separately and write down the quotient in the next line right under the respective integers. Bring down the integer to the next line if any integer in 28 and 30 is not divisible by the selected divisor; repeat the same process until all the integers are brought to 1 as like below:
| 2 | 28 | 30 |
| 2 | 14 | 15 |
| 3 | 7 | 15 |
| 5 | 7 | 5 |
| 7 | 7 | 1 |
| 1 | 1 |
step 4 Multiply the divisors to find the lcm of 28 and 30:
= 2 x 2 x 3 x 5 x 7
= 420
LCM(28, 30) = 420
The LCM of two numbers 28 and 30 is 420