LCM of 21 and 28 is equal to 84. The comprehensive work provides more insight of how to find what is the lcm of 21 and 28 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 28?
lcm (21 28) = (?)
21 => 3 x 7
28 => 2 x 2 x 7
= 7 x 3 x 2 x 2
= 84
lcm (21 and 28) = 84
84 is the lcm of 21 and 28.
where,
21 is a positive integer,
28 is a positive integer,
84 is the lcm of 21 and 28,
{7} in {3 x 7, 2 x 2 x 7} is the common factors of 21 and 28,
{3 x 2 x 2} in {3 x 7, 2 x 2 x 7} are the uncommon factors of 21 and 28.
Use in Mathematics: LCM of 21 and 28
The below are some of the mathematical applications where lcm of 21 and 28 can be used:
The below solved example with step by step work shows how to find what is the lcm of 21 and 28 by using prime factors method and division method.
Solved example using prime factors method:
What is the LCM of 21 and 28?
step 1
Address the input parameters, values and observe what to be found:
Input parameters and values:
A = 21
B = 28
What to be found:
find the lcm of 21 and 28
step 2 Find the prime factors of 21 and 28:
Prime factors of 21 = 3 x 7
Prime factors of 28 = 2 x 2 x 7
step 3 Identify the repeated and non-repeated prime factors of 21 and 28:
{7} is the most repeated factor and {3 x 2 x 2} are the non-repeated factors of 21 and 28.
step 4 Find the product of repeated and non-repeated prime factors of 21 and 28:
= 7 x 3 x 2 x 2
= 84
lcm(21 and 28) = 84
Hence,
lcm of 21 and 28 is 84
2 | 21 | 28 |
2 | 21 | 14 |
3 | 21 | 7 |
7 | 7 | 7 |
1 | 1 |