Most people think that in three dimensions the number 1 looks like the incorrect version drawn on the bottom right.
In fact it has been proven that the number 1 in three dimensional view actually has a planar base that extends in two dimensions from the stem of the 1.
Don’t take my word for it, try it for yourself at home!
Fun fact: this also applies to the fourth spatial dimension. If you take a 3D “slice” of the 4D point where the base meets the stem, the resulting 3D form will be a cube.
Also, the descender is actually a cone revolving around the W axis.