Option Explicit
Dim r,iArea
Const pi=3.1416
r=2.5
iArea="Global"

Main
PartII

Function Main()
'without DIM iArea will appear globally with Execute

Dim strExp,iArea
strExp="iArea=pi*(r*r)"
ExecuteGlobal strExp 'raises expression to the global scope
WScript.Echo "strExp = " & iArea 'returns nothing

End Function

Function PartII()
WScript.Echo "The formula result is: " & iArea 'returns 19.635

End Function