countdown in seconds / milliseconds (example below)

[real moth]

How do i make it so that when i run /spawn it sends a actionbar "Teleporting in: <seconds>.<millseconds>" So it will look like teleporting in 2.9 seconds, 2.8 seconds, 2.7 seconds ect... i have already got the loop + seconds how do i add milliseconds? next to it

[green bobcat]

if you are stringifying a timespan, skript will only display up to seconds by default.