This script[Sprite number for uGUI] can display Number on uGUI
At play time, it generates Images as much as necessary automatically.
In editing, you can check Gizmos of drawing range.
Topics
Drawing numbers of Sprite images
Setting Character width
high-order digits 0 drawing[on/off]
Display "+" or "-" number[on/off]
Display decimal point[on/off]
Alignment[Left/Center/Right]
Display debug-Gizmos
Thousand separator