| doodles asked how I did that...
First, I used a slow shutter speed (4/10 second), 100 ISO, and f/40 aperture - the goal being to keep the image from being overexposed.
I also have a 16-300mm Tamron zoom lens, and I changed the zoom during the exposure. (So, shutter release, zoom in (or out), shutter closes). Sounds easier than it is, and this was one of about 15 attempts. You don't have to have such an extreme range on the zoom to get the motion. This image happened to have a pause at each extreme, which is why the numbers seem to appear twice.
Finally, in processing, I did a negative image on it - the scene was actually of a building number just below the roof - light background with red numbers.