LCM (8,642; 86,420) = ? Least Common Multiple

Calculate the least common multiple, LCM (8,642; 86,420), using their prime factorizations, numbers' divisibility or the Euclidean algorithm

Method 1. The divisibility of numbers:

A number 'a' is divisible by a number 'b' if there is no remainder when 'a' is divided by 'b'.


Divide the larger number by the smaller one.

When we divide our numbers, there is no remainder:

86,420 ÷ 8,642 = 10 + 0

⇒ 86,420 = 8,642 × 10

⇒ 86,420 is divisible by 8,642.

⇒ 86,420 is a multiple of 8,642.

The smallest multiple of 86,420 is the number itself: 86,420.

» Online calculator. The divisibility of numbers


The least common multiple:
lcm (8,642; 86,420) = 86,420 = 22 × 5 × 29 × 149
86,420 is a multiple of 8,642
Scroll down for the 2nd method...

Method 2. The prime factorization:

The prime factorization of a number: finding the prime numbers that multiply together to make that number.

8,642 = 2 × 29 × 149
8,642 is not a prime number but a composite one.

86,420 = 22 × 5 × 29 × 149
86,420 is not a prime number but a composite one.

» Online calculator. Check whether a number is prime or not. The prime factorization of composite numbers

* Prime number: a natural number that is only divisible by 1 and itself. A prime number has exactly two factors: 1 and itself.
* Composite number: a natural number that has at least one other factor than 1 and itself.


Calculate the least common multiple, lcm:

Multiply all the prime factors of the two numbers. If there are common prime factors then only the ones with the largest exponents are taken (the largest powers).


The least common multiple:
lcm (8,642; 86,420) = 22 × 5 × 29 × 149 = 86,420
86,420 contains all the prime factors of the number 8,642

Why is it useful to calculate the least common multiple?

In order to add, subtract or sort fractions with different denominators, we must make their denominators the same. An easy way is to calculate the least common multiple of all the denominators (the least common denominator).

By definition, the least common multiple of two numbers is the smallest natural number that is: (1) greater than 0 and (2) a multiple of both numbers.


Other similar operations with the least common multiple:

» What is the least common multiple, LCM, of the numbers 8,593 and 86,407?

» New. All the Calculations Performed by Our Visitors: Calculated Values of the Least (the Lowest) Common Multiple, lcm, of Pairs of Numbers. Data organized on a Monthly Basis

The least common multiple (lcm). What it is and how to calculate it.

  • The number 60 is a common multiple of the numbers 6 and 15 because 60 is a multiple of 6 (60 = 6 × 10) and also a multiple of 15 (60 = 15 × 4).
  • There are infinitely many common multiples of 6 and 15.
  • If the number "v" is a multiple of the numbers "a" and "b", then all the multiples of "v" are also multiples of "a" and "b".
  • The common multiples of 6 and 15 are the numbers 30, 60, 90, 120, and so on.
  • Out of these, 30 is the smallest, 30 is the least common multiple (lcm) of 6 and 15.
  • Note: The prime factorization of a number: finding the prime numbers that multiply together to give that number.
  • If e = lcm (a, b), then the prime factorization of "e" must contain all the prime factors involved in the prime factorization of "a" and "b" taken by the highest power.
  • Example:
  • 40 = 23 × 5
  • 36 = 22 × 32
  • 126 = 2 × 32 × 7
  • lcm (40, 36, 126) = 23 × 32 × 5 × 7 = 2,520
  • Note: 23 = 2 × 2 × 2 = 8. We are saying that 2 was raised to the power of 3. Or, shorter, 2 to the power of 3. In this example 3 is the exponent and 2 is the base. The exponent indicates how many times the base is multiplied by itself. 23 is the power and 8 is the value of the power:
  • Another example of calculating the least common multiple, lcm:
  • 938 = 2 × 7 × 67
  • 982 = 2 × 491
  • 743 = is a prime number and cannot be broken down into other prime factors
  • lcm (938, 982, 743) = 2 × 7 × 67 × 491 × 743 = 342,194,594
  • If two or more numbers have no common factors (they are coprime), then their least common multiple is calculated by simply multiplying the numbers.
  • Example:
  • 6 = 2 × 3
  • 35 = 5 × 7
  • lcm (6, 35) = 2 × 3 × 5 × 7 = 6 × 35 = 210