How to use the LCM function
What is the LCM function?
The LCM function calculates the least common multiple.
Table of Contents
1. Introduction
What is the least common multiplier?
The least common multiple is the smallest positive integer that is a multiple of all integer arguments.
When is the LCM function useful?
Use the LCM function to find fractions with different denominators.
What is a fraction?
A fraction has a numerator and a denominator:
- Numerator - The top number in a fraction.
- Denominator - The bottom number.
For example:
6/7
- The numerator is 6, meaning 6 parts.
- The denominator is 7, meaning the whole was split into 7 equal parts.
How is the least common multiple calculated?
Finding least common multiples is the product of two numbers divided by their greatest common divisor.
For example,
least common multiple(number1,number2) = (number1*number2) / greatest common divisor(number1,number2).
least common multiple(6,8) = 6*8/2 = 48/2 = 24
What is the greatest common divisor?
The greatest common divisor of two or more integers is the largest integer that divides them all. For two numbers number1 and number2, it is the largest integer that divides both number1 and number2 without remainder.
For example:
greatest common divisor(8,12) = 4
This is because 4 is the largest number that divides both 8 and 12.
greatest common divisor(18,24) = 6
6 is the greatest common factor of 18 and 24.
greatest common divisor(10,15,25) = 5
5 is the largest number that divides 10, 15 and 25.
What is a remainder?
A remainder is the amount left over after dividing two integers.
The remainder is what is left after dividing two integers. If you divide 15 with 2 you get 7 and 1 is left over. 2*7 equals 14. 15 - 14 equals 1. The remainder is 1.
What is a divisor?
A divisor is a number that divides into another number either cleanly or leaving a remainder.
dividend / divisor = quotient( + remainder)
What is a dividend?
In division, the dividend is the number being divided.
For example, in the division:
15 / 5 = 3
15 is the dividend 5 is the divisor and 3 is the quotient
What is a quotient?
The quotient is the result when two numbers are divided.
What is a factor?
A factor is a number that divides evenly into another number, in other words, without leaving a remainder.
When is the greatest common divisor useful?
The GCD can be used to reduce fractions to their simplest form. For example, greatest common divisor(36,68) = 4 can simplify 36/68 to 9/17.
What other Excel functions are about division, dividend, divisor, and quotient?
Excel Function | Description |
GCD | Returns the greatest common divisor of two numbers |
LCM | Returns the least common multiple of two numbers |
QUOTIENT | Returns the integer portion of a division between two numbers |
MOD | Returns the remainder after dividing num1 by num2 |
2. Syntax
LCM(number1, [number2], ...)
number1 | Required. The number you want to calculate the least common multiple for. |
[number2] | Optional. Up to 254 additional numbers. |
The LCM function returns an error value if any argument is not a number.
3. Example
This example demonstrates how to calculate the least common multiple using the LCM function. The image above shows the arguments in cell range B3:C7 and the results in cell range E3:E7.
The first argument pair is 3 and 4 which are displayed in cells B3:C3 respectively. Cell E3 which contains the formula below returns 12. 12 is the least common multiple based on 3 and 4.
Formula in cell E3:
Lets calculate this manually:
First we need to calculate the greatest common divisor.
- Divide a by b and get the quotient q and remainder r, such that a = b * q + r.
a = 4, b = 3
a / b = 1 + 1, q = 1, r = 1 - If r ≠ 0, then greatest common divisor(a, b) = greatest common divisor(b, r), since the greatest common divisor of a and b is the same as the greatest common divisor of b and the remainder r.
- Replace a with b and b with r, and repeat above steps until the remainder becomes 0.
a = 3, b = 1
a/b = 3 + 0, q = 3, r = 0 - If r = 0, then greatest common divisor(a, b) = b, since b is a divisor of a.
greatest common divisor(3, 1) = 1
The greatest common divisor is 1 based on values 4 and 3.
Finding least common multiples is the product of two numbers divided by their greatest common divisor.
least common multiple(number1,number2) = (number1*number2) / greatest common divisor(number1,number2).
least common multiple(4,3) = 4*3/1 = 12/1 = 12
Our calculated value 12 matches the result in cell E3.
The second argument pair is 24 and 46 which are displayed in cells B4:C4 respectively. Cell E4 which contains the formula below returns 552. 552 is the least common multiple based on 24 and 46.
Formula in cell E4:
Lets calculate this manually:
First we need to calculate the greatest common divisor.
- Divide a by b and get the quotient q and remainder r, such that a = b * q + r.
a = 46, b = 24
a / b = 1 + 22, q = 1, r = 22 - If r ≠ 0, then greatest common divisor(a, b) = greatest common divisor(b, r), since the greatest common divisor of a and b is the same as the greatest common divisor of b and the remainder r.
- Replace a with b and b with r, and repeat above steps until the remainder becomes 0.
a = 24, b = 22
a/b = 1 + 2, q = 1, r = 2 - Replace a with b and b with r, and repeat above steps until the remainder becomes 0.
- a = 22, b = 2
a/b = 11 + 0, q = 11, r = 0 - If r = 0, then greatest common divisor(a, b) = b, since b is a divisor of a.
greatest common divisor(46, 24) = 2
The greatest common divisor is 1 based on values 46 and 24.
Finding least common multiples is the product of two numbers divided by their greatest common divisor.
least common multiple(number1,number2) = (number1*number2) / greatest common divisor(number1,number2).
least common multiple(46,24) = 46*24/2 = 1104/2 = 552
Our calculated value 552 matches the result in cell E4.
The third argument pair is 12 and 4 which are displayed in cells B5:C5 respectively. Cell E5 which contains the formula below returns 12. 12 is the least common multiple based on 12 and 4.
Formula in cell E4:
Lets calculate this manually:
First we need to calculate the greatest common divisor.
- Divide a by b and get the quotient q and remainder r, such that a = b * q + r.
a = 12, b = 4
a / b = 3 + 0, q = 3, r = 0 - If r = 0, then greatest common divisor(a, b) = b, since b is a divisor of a.
greatest common divisor(12, 4) = 4
The greatest common divisor is 4 based on values 12 and 4.
Finding least common multiples is the product of two numbers divided by their greatest common divisor.
least common multiple(number1,number2) = (number1*number2) / greatest common divisor(number1,number2).
least common multiple(12,4) = 12*4/4 = 12
Our calculated value 12 matches the result in cell E4.
Functions in 'Math and trigonometry' category
The LCM function function is one of 62 functions in the 'Math and trigonometry' category.
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