[Let] variablename = expression
Let assigns a value to a variable.
Let is an optional keyword that is rarely used. The Let statement is required in older versions of BASIC.
Example:
Sub Form_Click ()
Dim Msg, Pi ' Declare variables.
Let Pi = 4 * Atn(1) ' Calculate Pi.
Msg = "Pi is equal to " & Str(Pi)
MsgBox Msg ' Display results.
End Sub