How exactly do I make a comma in a number?

I'm trying to make a comma in a number (250436186) but I want it to say 250,436,186. I know I can use If statements, But I want like the text to change...

Heres what I got (With IF STATEMENTS)

local Text = game.Workspace.Sign.Gui.TEXT

if Text.Text == "250436186" then
	Text.Text = "250,436,186"
end

But What if I wanted a For i statement? That's what I'm trying...

Heres what I got

local Text = game.Workspace.Sign.Gui.TEXT

for i = 1000,600000000,554 do
	if i ~= 1 then
		Text.Text = i
	end
	wait(0.01)
end

I'm trying to add a comma into The I statement That's all I'm doing...