How to Find LCM in VB.Net | Step-by-Step Tutorial

What is LCM? | Maths Explanation for VB.Net Kids

Akin to finding H.C.F., L.C.M. is commonly found by repeated factorization. Only this time, the factors do not have to be common amongst the set of numbers.

If we have the set of numbers 8, 12 and 18 for example, their L.C.M. is found thus:

Hence, L.C.M. of 8, 12 and 18 = 2 X 2 X 2 x 3 x 3 = 72

Step-by-Step Guide to L.C.M. by Factorisation in VB.Net

We shall follow the steps below in writing our Visual Basic LCM code.

Step 1:

Do a numerical reverse sort on the (resulting) set so its first member is the largest in the set.

Step 2:

Starting with 2, iteratively check through the set of numbers for individual factors.

Step 3:

For each individual factor, divide affected member(s) of the number set by the factor.

Step 4:

Repeat the above steps recursively until there are no more individual factors.

Create a new VB.Net class file; Project, Add Class.
Call it findLCM.vb.
Optionally, Create a new VB.Net module file; Project, Add Module.
Call it FindLCMModule.vb.

Type out the adjoining Visual Basic (VB.Net) code for finding Lowest Common Multiple (L.C.M.)

Note: You can just reuse the VB.Net main module from the previous lesson if you have been following.

So! Visual Basic Fun Practice Exercise - Find LCM

As a fun practice exercise, feel free to try out your own numbers, and see how the Visual Basic code finds the LCM of those numbers.

VB.Net Code for Find LCM - Class File.

Public Class LCM

    Dim set_of_numbers As New List(Of Integer) ' will hold the the values to be sent in
    Dim all_factors As New List(Of Integer) ' for housing all common factors
    Dim state_check As Boolean
    Dim calc_result As Integer
    Dim index As Integer

    ' A constructor
    Public Sub _init_(group As List(Of Integer))
        For Each member In group
            set_of_numbers.Add(member)
        Next
        ' Sort array in descending order
        set_of_numbers.Sort()
        set_of_numbers.Reverse()

        index = 1
        state_check = False
        calc_result = 1
    End Sub

    Private Function findLCMFactors() As List(Of Integer)
        '  Copy 'set_of_numbers' into 'arg_copy'
        Dim arg_copy As New List(Of Integer)
        For Each number In set_of_numbers
            arg_copy.Add(number)
        Next
        ' STEP 1:
        ' sort in descending order
        arg_copy.Sort()
        arg_copy.Reverse()

        Do While index <= arg_copy.Item(0)
            state_check = False
            For count_off = 0 To set_of_numbers.Count - 1
                If set_of_numbers.Item(count_off) Mod index = 0 Then
                    ' STEP 3:
                    set_of_numbers.Item(count_off) = CInt(set_of_numbers.Item(count_off) / index)
                    If state_check = False Then
                        all_factors.Add(index)
                    End If

                    state_check = True ' do Not store the factor twice
                End If
            Next count_off

            ' STEP 4:
            If state_check Then
                Return findLCMFactors()
            End If

            index += 1
        Loop

        Return Nothing
    End Function

    ' Returns an array reference Of the desired Set Of even numbers
    Public Function getLCM() As Integer
        ' STEP 2:
        index = 2
        findLCMFactors()

        ' iterate through And retrieve members
        For Each factor In all_factors
            calc_result *= factor
        Next factor

        Return calc_result
    End Function

End Class

VB.Net Code for Find LCM - Main Module.

Module Arithmetic_LCM

    Sub Main()

        ' Use the LCM Class
        Dim group As New List(Of Integer)({20, 30, 40})
        Dim lcm As New LCM
        lcm._init_(group)
        Dim answer = lcm.getLCM()

        Console.Write("The L.C.M. of " & String.Join(", ", group) & " is " & answer)

    End Sub

End Module

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