Creating a program in VB2015 that generates geometric progression

We can write a VB2015 to generate generate a geometric progression based on the following formula:

the nth term of a GP is ar^n-1, where a is the first term, r the common ratio and n is the number of terms.

To create the code, we insert the following controls:

List Box- to display the output

textbox 1 – to let user input the first number
textbox 2 – to let user input the common ratio
textbox3 – to let user input the number of terms.

We use the syntax


to add the numbers generated to the list box

And we use the do loop to generate the numbers.

The Code

Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim n, num As Integer
Dim x, r As Single
x = Txt_FirstNum.Text
r = Txt_CR.Text
num = Txt_terms.Text
ListBox1.Items.Add(“n” & vbTab & “x”)

n = 1
ListBox1.Items.Add(n & vbTab & x)
x = x * r

n = n + 1
ListBox1.Items.Add(n & vbTab & Format(x, “0.00”))
Loop Until n = num + 1
End Sub

End Class

The Design Interface


The Output