Excel Technique: LCM & HCF (or GCD)

Age 11 to 16 Challenge Level:

Excel has two useful functions for work with fractions : LCM & GCD.

=LCM(number1, number2, . . . ) returns the lowest common multiple of a set of integers, that is the smallest positive integer that is a multiple of all integer arguments number1, number2, and so on.

The LCM gives the new denominator for adding or subtracting fractions with different denominators.

=GCD(number1, number2, . . . ) returns the largest integer that is a factor of all the integers.

GCD finds the common factor required to reduce a fraction to its simplest form. 6/9 becomes 2/3 because 6 and 9 both contain a factor of 3.

If these functions are not available, run the Setup program to install Analysis ToolPak.

After you install the Analysis ToolPak, you must enable it by using the Add-Ins command on the Tools menu.