comment your opinion A,B,C,D

I’m uploading a calculator, and I’m wondering what part count level it should be at
A~700
B~1,000
C~1,300
D~1,600
These part counts correspond to its ability to do math, the max output answers for these are,
A~7(4+3)
B~15(8+7)
C~31(16+15)
D~63(32+31)
Note that these are all the highest inputs and all other variations below the values work