Function help

[Inugami]

Hello i recently started to use functions but do not understand the concept. I have worked on a project out of a book that adds coins(quarters, dimes, nickels, pennies) and adds them all up using a function. This is what i have done:

Dim sngCalculate As Single
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Private Sub btnAddCoins_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAddCoins.Click
Dim sngQuarters As Single = Val(Me.txtValue1.Text)
Dim sngDimes As Single = Val(Me.txtValue2.Text)
Dim sngNickels As Single = Val(Me.txtValue3.Text)
Dim sngPennies As Single = Val(Me.txtValue4.Text)

sngQuarters = sngQuarters * 25
sngDimes = sngDimes * 5
sngNickels = sngNickels * 10
sngPennies = sngPennies * 1

Me.lblAnswer.Text = Calculate(sngCalculate)
End Sub
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Function Calculate(ByVal sngQuarters As Single, ByVal sngDimes _
As Single, ByVal sngNickels As Single, ByVal sngPennies As Single) As Single

sngCalculate = sngQuarters * sngDimes * sngNickels * sngPennies
Return sngCalculate
End Function

End Class

This does not work and i am uncertain of if i am doing the function correctly. Any help would be greatly appreciated. So far it adds everything to 0.