Fluorescent ink is a special kind of ink, which can emit fluorescence under ultraviolet light or purple light, but this fluorescence is invisible under ordinary sunlight. Therefore, fluorescent ink can't copy fluorescent numbers on ordinary photocopiers.

However, color copiers are different from ordinary copiers. The color copier can recognize not only ordinary ink, but also fluorescent ink. When using a color copier, if fluorescent ink is added to the ink cartridge, the copier can recognize and copy the fluorescent numbers.