Doing this in material only is not easy task, so if you insist (or if its really that you need it as material, we can dig into that later)
There is “render text” component. You could make your block plus render text actor as single blueprint, expose on spawn text to render. Then manipulate those blueprint actors instead off blocks.
To make this work: create new blueprint, lets say BP_Block, add 2 components to it: block and render text. Create variable that holds text to display, and maybe second for text color etc. Expose them to editor and on spawn.
Now to add those actors from another bp: you spawn actor from class and use BP_Block as its class.
But if you want more than 200-300ish of those blocks then indeed you need single mesh with material per one.
So if you really need that display digit material:
- give me exact shape of block, ie dimensions if its box,
- which faces and orientation you want to have digits displayed, this is needed for uv mapping of mesh
If i have time this weekend i can make mesh, material for it and uv layout texture.