Sub Demo()
Dim Tbl As Table, r As Long, c As Long, Rslt, sMul As Single, Rng As Range
Rslt = InputBox("What is the multiplier?")
If IsNumeric(Rslt) = False Then Exit Sub
sMul = CSng(Rslt)
For Each Tbl In ActiveDocument.Tables
  With Tbl
    For r = 3 To .Rows.Count
      For c = 2 To .Columns.Count
        With .Cell(r, c)
          Set Rng = .Range
          Rslt = Split(Split(Rng.Text, vbCr)(0), " ")(0)
          If IsNumeric(Rslt) Then
            Rng.End = Rng.Start + Len(Rslt)
            Rng.Text = Rslt * sMul
          End If
        End With
      Next
    Next
  End With
Next
End Sub