Text inside a number

I've done this type of thing many times. It takes a little preparation and work.
Prepare a piece of paper for the students to sign. Print the outline of the numbers on the paper at actual size. Just the outline with the insides of the numbers in plain white. Write big instructions on it telling the kids "DON'T SIGN OUTSIDE THE NUMBERS. DON'T LET YOUR SIGNATURE TOUCH THE OUTLINE."
Have the students sign in black fine-tip Sharpie marker.
Once they are done signing, scan the signature page in at high resolution and open it in Photoshop. Ctrl+H and desaturate the image. Ctrl+L and adjust the levels so it's just straight black and white with no gray. Remove the outline of the numbers from the image by painting in white or erasing.
At that point I would Select-Color Range and select the signatures. Then make a new layer and add the signatures to the new layer with a transparent background. Color the signatures appropriately. Then save and import the signatures into your vector drawing program and add them to your design.

About four years ago, we had a request for this (about 190-200 names). We did it name by name instead of having the kids sign inside a shape because the client wanted to use the signatures for other shapes and items as well.

If you have photoshop and a scanner, it's simple.
-At a senior class meeting, have kids sign their names on plain paper (definitely have someone responsible watch and instruct)
-Keep names per page to about 20 or 30 to allow enough clear space for clipping / cutting around the signature cleanly.
-Once you have all the sheets, scan them in (200-300 dpi should be good)
-Once you have the scans, in PS, increase the saturation in the black channel to really make the signatures dark.
-Select the magic wand, click the white area, and delete the white. Then lasso each name and cut them as a layer.

Do this until you have all the names cut out.

For whatever shape or space you want to put the names in, copy the name layer, then select the space / shape (the shape should have the "marching ants" activity visible), then use "Paste Into" command...VIOLA'! Your scanned name is now inside of the shape.

Repeat until complete.

Seems like a lot of work but took us less than an hour. Your graphic fee should more than compensate you for your time if doing this for a paying client.

Cool thing is we did 3 more shapes/items for them that year...charged the same graphics fee for each but only took about ten minutes! Once you have the names as individual layers, the rest is cake and skies the limit for what you can do with them.

Hope this helps,