I don't remember 15 having such curly hair...and why is she so nervous? And where'd Six and Nine go?

Nine with no shades. blue eyes

*Stanley Parable voice* Eight

another thing about teeth. how many of you care that I gave Two a second pair of fangs sticking out of their mouth (+edit to drive that detail further)

More about X! He has Oni tusks and X-shaped pupils, plus I tried to reflect the fancy X written in Algebraic expressions
(and Cary has a habit of drawing them with brown eyes)

I'm sure you already noticed the number of tails they have correspond to their values, double digits have a different tail end shape and variables like X have split tails!

I put 14's head at a weird angle so here's a close up. They muzzled him because he bites + I had Hannibal Lecter in mind when drawing him

The mismatched teeth on One are intentional, the right angle can make it look like she only has one fang sticking out

One and Three are dots and I connected them