Whats wrong with my countdown script?

for i = 60,0,-1 do
script.Parent.Text = "Time remaining: 3:"..i

I'm trying to make it a countdown of 3 minutes, but how do I change the minutes too when the seconds hit 0 and the seconds keep going? For example; 3:00 minutes, 2:59, 2:58, etc. When it hits 2:00, how will I change that? Please help!

Hey, dude!

for i = 60,0,-1 do
	script.Parent.Text = "Time remaining: 2:" ..i
	wait(1)
end
for i = 60,0,-1 do
	script.Parent.Text = "Time remaining: 1:" ..i
	wait(1)
end
for i = 60,0,-1 do
	script.Parent.Text = "Time remaining: :" ..i
	wait(1)
end

There, edited.