Try this it does what your example shows

Sub Button1_Click()
Dim s As String
s = InputBox("What is the number")
Range("A1") = s
Range("B1:D1").FormulaR1C1 = "=RC[-1]+20"
Range("A1:D1").AutoFill Destination:=Range("A1:D20"),
Type:=xlFillDefault
End Sub