Im trying to make a block fade in and out. Why is transparency going to 1.1 and -0.1?

Im new to scripting and am trying to create a sphere that continuously fades in and out. I have it working with this script although the transparency will go up to 1.1 and -0.1 and I cant figure out why. Heres what I have.

sphere = script.Parent
transparency = 0
fadeOut = true

while true do
	if transparency <= 0 then
		fadeOut = true
	elseif transparency >= 1 then
		fadeOut = false
	end
	
	if fadeOut then
		transparency = transparency + 0.1
		sphere.Transparency = transparency
	else -- fadein
		transparency = transparency - 0.1
		sphere.Transparency = transparency
	end
	wait(1)
end

After looking at this, I am not sure of this reason either... I can make a guess that maybe it is because of floating point rounding error. Article

What I can tell you is that there is a better way of doing this. Consider using Tween's to do this:

Here is how you would do your fade thing:

sphere = script.Parent

local goal = {}
goal.Transparency = 1	--Assuming that the original transparency is 0

game:GetService("TweenService"):Create(sphere, TweenInfo.new(1, Enum.EasingStyle.Back, Enum.EasingDirection.In, -1, true), goal)

This should work tho I haven't tested it. I recommend you read this: Tween Service

There's a more efficient way to make it.

sphere = script.Parent --- Make sure this is where the object you want to fade in and out transparency
start = 0
goal = 1
----
sphere.Transparency = start --- Ensure you start from transparency 0

while wait() do
	for i = 1,10 do
		sphere.Transparency = sphere.Transparency + 0.1
	end
	for i = 1,10 do
		sphere.Transparency = sphere.Transparency - 0.1
	end
end