What can I do to make a Gui Timer?

I am trying to make a timer using a Gui, however it seems like I cannot use numbers as a value for the text of the gui. Can you give me a solution to this or another way to make a Gui timer? i do not want to use a free model.

easy,

gui = gui
timevalue = script.Parent.TimeValue
max =  script.Parent.TimeValue.Value
for i = 1, timevalue.Value do
wait(1)
gui.Text = tostring(max-timevalue.Value)
timevalue.Value = timevalue.Value - 1
end

And for the certain command, look into .Chatted functions. and study string maniuplations such as string:sub() and string:lower() which would be helpfull in your situation.