She, and all the other figured-out Numberblocks bigger than Thirty, (except for the Orders of Magnitude) were probably figured out by going through the six-step plan seen in Figure It Out, which could possibly explain why she was figured out offscreen; the writers wanted to avoid creating too many similar episodes.
She is the first Numberblock in the forties appearing in their figured-out form. If Forty-Two counts, then she would be second.
She is the first odd super rectangle.
She is the second