LCM of 39, 42 and 91
546 is the LCM of 39, 42 and 91. 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 39, 42 and 91, provided along with the use cases of mathematics and real-world problems.
what is the lcm of 39, 42 and 91?
lcm (39 42 91) = (?)
39 => 3 x 13
42 => 2 x 3 x 7
91 => 7 x 13
= 3 x 7 x 13 x 2
= 546
lcm (39, 42 and 91) = 546
The LCM of 39, 42 and 91 is 546
where,
39 is a positive integer,
42 is a positive integer,
546 is the LCM of 39, 42 and 91,
{3, 7, 13} in {3 x 13, 2 x 3 x 7, 7 x 13} are the most repeated factors of 39, 42 and 91,
{2} in {3 x 13, 2 x 3 x 7, 7 x 13} is the other remaining factors of 39, 42 and 91.
Use in Mathematics: LCM of 39, 42 and 91
The below are some of the mathematical applications where lcm of 39, 42 and 91 can be used:
- to find the least number which is exactly divisible by 39, 42 and 91.
- to find the common denominators for the fractions having 39, 42 and 91 as denominators in the unlike fractions addition or subtraction.
In the context of lcm real world problems, the lcm of 39, 42 and 91 helps to find the exact time when three similar and recurring 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 all the bells A, B and C toll together, if bell A tolls at 39 seconds, B tolls at 42 seconds and C tolls at 91 seconds repeatedly. The answer is that all bells A, B and C toll together at 546 seconds for the first time, at 1092 seconds for the second time, at 1638 seconds for the third time and so on.
Important Notes: 39, 42 and 91 lcm
The below are the important notes to be remembered while solving the lcm of 39, 42 and 91:
- The repeated and non-repeated prime factors of 39, 42 and 91 should be multiplied to find the least common multiple of 39, 42 and 91, when solving lcm by using prime factors method.
- The results of lcm of 39, 42 and 91 is identical even if we change the order of given numbers in the lcm calculation, it means the order of given numbers in the lcm calculation doesn't affect the results.
How-to: What is LCM of 39, 42 and 91?
The below solved example with step by step work shows how to find what is the lcm of 39, 42 and 91 by using either prime factors method and special division method.
Solved example using prime factors method:
What is LCM of 39, 42 and 91?
step 1
Address the input parameters, values and observe what to be found:
Input parameters and values:
A = 39
B = 42
C = 91
What to be found:
Find lcm of 39, 42 and 91
step 2 Find the prime factors of 39, 42 and 91:
Prime factors of 39 = 3 x 13
Prime factors of 42 = 2 x 3 x 7
Prime factors of 91 = 7 x 13
step 3 Identify the repeated and non-repeated prime factors of 39, 42 and 91:
{3, 7, 13} are the most repeated factors and {2} is the non-repeated factors of 39, 42 and 91.
step 4 Find the product of repeated and non-repeated prime factors of 39, 42 and 91:
= 3 x 7 x 13 x 2
= 546
LCM(39, 42 and 91) = 546
Hence,
The Least Common Multiple of 39, 42 and 91 is 546
This special division method is one of the easiest ways to understand the entire calculation to find the LCM of 39, 42 and 91.
step 1 Address the input parameters, values and observe what to be found:
Input parameters and values:
Integers: 39, 42 and 91
What to be found:
lcm (39, 42, 91) = ?
step 2 Arrange the given integers in the horizontal form with space or comma separated format:
39, 42 and 91
step 3 Choose the divisor which divides each or most of the given integers (39, 42 and 91), 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 39, 42 and 91 is not divisible by the selected divisor; repeat the same process until all the integers are brought to 1 as like below:
| 2 | 39 | 42 | 91 |
| 3 | 39 | 21 | 91 |
| 7 | 13 | 7 | 91 |
| 13 | 13 | 1 | 13 |
| 1 | 1 | 1 |
step 4 Multiply the divisors to find the lcm of 39, 42 and 91:
= 2 x 3 x 7 x 13
= 546
LCM(39, 42, 91) = 546
The LCM of three numbers 39, 42 and 91 is 546