How could I shorten this script down to make it easier?

I want to make a countdown script, but I think it's going to take me over an hour to finish. How could I shorten this?

while true do

script.Parent.Text = "7:00"
wait(1)

script.Parent.Text = "6:59"
wait(1)

script.Parent.Text = "6:58"
wait(1)

-- Right down to 0:00

Thanks for your help :)

You can use a for loop. It's pretty awesome.

NumberOfSeconds = 420

for i = NumberOfSeconds, 0, -1 do
	script.Parent.Text = i
	wait(1)
end

For every second, the text property will display the current number of seconds.

You can also add some math stuff so it would display "7:00" instead of "420."