How do I add up and find the sum of all the numbers in TextLabels?

How do I add up and find the sum of all the numbers in TextLabels?

 local local0 = 0
 script.Parent.MouseButton1Click:Connect(function()
 local0 += 1
 game.Workspace["Town Hall"]["iSlim Computer"].Screenn.SurfaceGui.TextLabel.Text = local0
 game.Workspace["Town Hall"]["iWatch TV"].Screenn.SurfaceGui.TextLabel.Text = local0
 end)