# 21 and 49 LCM LCM of 21 and 49 is equal to 147. The comprehensive work provides more insight of how to find what is the lcm of 21 and 49 by using prime factors and special division methods, and the example use case of mathematics and real world problems.

what is the lcm of 21 and 49?
lcm (21   49) = (?)
21 => 3 x 7
49 => 7 x 7

= 7 x 3 x 7
= 147
lcm (21 and 49) = 147
147 is the lcm of 21 and 49.

where,
21 is a positive integer,
49 is a positive integer,
147 is the lcm of 21 and 49,
{7} in {3 x 7, 7 x 7} is the common factors of 21 and 49,
{3 x 7} in {3 x 7, 7 x 7} are the uncommon factors of 21 and 49.

Use in Mathematics: LCM of 21 and 49
The below are some of the mathematical applications where lcm of 21 and 49 can be used:

1. to find the least number which is exactly divisible by 21 and 49.
2. to find the common denominator for two fractions having 21 and 49 as denominators in the unlike fractions addition or subtraction.
Use in Real-world Problems: 21 and 49 lcm
In the context of lcm real world problems, the lcm of 21 and 49 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 21 seconds and bell B tolls at 49 seconds repeatedly. The answer is that all bells A and B toll together at 147 seconds for the first time, at 294 seconds for the second time, at 441 seconds for the third time and so on.

Important Notes: 21 and 49 lcm
The below are the important notes to be remembered while solving the lcm of 21 and 49:
1. The common prime factors and the remaining prime factors of 21 and 49 should be multiplied to find the least common multiple of 21 and 49, when solving lcm by using prime factors method.
2. The results of lcm of 21 and 49, and the lcm of 49 and 21 are identical, it means the order of given numbers in the lcm calculation doesn't affect the results.
For values other than 21 and 49, use this below tool:

## How-to: What is the LCM of 21 and 49?

The below solved example with step by step work shows how to find what is the lcm of 21 and 49 by using prime factors method and division method.

Solved example using prime factors method:
What is the LCM of 21 and 49?

step 1 Address the input parameters, values and observe what to be found:
Input parameters and values:
A = 21
B = 49

What to be found:
find the lcm of 21 and 49

step 2 Find the prime factors of 21 and 49:
Prime factors of 21 = 3 x 7
Prime factors of 49 = 7 x 7

step 3 Identify the repeated and non-repeated prime factors of 21 and 49:
{7} is the most repeated factor and {3 x 7} are the non-repeated factors of 21 and 49.

step 4 Find the product of repeated and non-repeated prime factors of 21 and 49:
= 7 x 3 x 7
= 147
lcm(21 and 49) = 147

Hence,
lcm of 21 and 49 is 147

Solved example using special division method:
This special division method is the easiest way to understand the entire calculation of what is the lcm of 21 and 49.

step 1 Address the input parameters, values and observe what to be found:
Input parameters and values:
Integers: 21 and 49

What to be found:
lcm (21, 49) = ?

step 2 Arrange the given integers in the horizontal form with space or comma separated format:
21 and 49

step 3 Choose the divisor which divides each or most of the given integers (21 and 49), 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 21 and 49 is not divisible by the selected divisor; repeat the same process until all the integers are brought to 1 as like below:

 3 21 49 7 7 49 7 1 7 1 1

step 4 Multiply the divisors to find the lcm of 21 and 49:
= 3 x 7 x 7
= 147
LCM(21, 49) = 147

The least common multiple for two numbers 21 and 49 is 147 