Excel Technique: LCM & HCF (or GCD)

Stage: 3 and 4 Challenge Level: Challenge Level:2 Challenge Level:2

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.
The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice. More information on many of our other activities can be found here.
Copyright © 1997 - 2012. University of Cambridge. All rights reserved.
NRICH is part of the family of activities in the Millennium Mathematics Project.