Why is this timer script not working right?

So the timer script is supposed to stop once everything reaches 0. However, it doesn't, and I don't know why. The script is pretty crude, so that could be a problem. Can someone please help me?

Here's the script (Yes, everything is defined):

local Seconds = script.Parent.Seconds
local Minutes = script.Parent.Minutes

while true do
	if script.Parent.TimesUp.Value == false then
	Seconds.Value = Seconds.Value - 1
		if Seconds.Value == 0 and script.Parent.TimesUp.Value == false then
			Minutes.Value = Minutes.Value - 1
			Seconds.Value = 59
		end
		if Seconds.Value == 10 and Minutes.Value == 0 then
			script.Parent.Backup.Value = 0
		end
	end
	if script.Parent.Backup.Value == 0 and Seconds.Value == 0 then
		script.Parent.TimesUp.Value = true
	end
	wait(1)
end

The problem is that you are skipping 0 seconds. -- That actually means your "minutes" are 59 seconds long.

Look at line 7 and then 9; now look at line 15.

Like 7-9 say: "If seconds are 0, then seconds will now be 59."

Immediately following, line 15 asks, "are seconds 60?" which will clearly always be no.

I think the solution to fix both of these problems is to change 59 to 60, and check for 60 or 0 (0 only for when the timer starts at 0 seconds).

If you want a better overall way of doing it, here it is:

Only count in seconds. (If you need to generate a time from a minute, second pair just use 60 * minutes + seconds)

We can still get the number of minutes out by using remainder after addition.

Here is what it would look like:

while seconds > 0 do
	wait(1)
	seconds = seconds - 1
	print( math.floor(seconds / 60) , ":", seconds % 60)
	-- minutes : seconds
end

This should be more efficient (:

local Seconds = script.Parent.Seconds
local Minutes = script.Parent.Minutes

while true do
	if script.Parent.TimesUp.Value == false then
		if Seconds.Value > 0 then
			Seconds.Value = Seconds.Value -1
		elseif Seconds.Value <= 0 and Minutes.Value >= 1 then
			Minutes.Value = Minutes.Value - 1
			Seconds.Value = 59
		elseif Seconds.Value <=0 and Minutes.Value <= 0 then
			script.Parent.TimesUp.Value = true
		end
	end
	wait(1)
end