How do I slow down the counting for a numbervalue?

Basically what I'm trying to do is make a progress bar that will sometimes change to be slowed for certain actions and be normal speed for other actions. The progress is stored in a number value but when I tell the script to divide the counting by 2, it cuts the current number in half and THEN it counts slower. I am just trying to make it count slower. [sorry if the title isn't completely accurate, I didn't know what to title it]

while true do
    elapsed.Value = tick()-start_time
    elapsed.Value = elapsed.Value/2
    wait(0.01)
end

(there is more to it obviously)

I have been struggling for hours to try to find workarounds, but I just haven't seen one.

Thanks.