Numerical answer type, tolerance 0.5.
Answer: 4
The ketone shown is 2-methylcyclopentanone with alpha carbons C2 and C5. Methylation at C2 gives 2,2-dimethylcyclopentanone (achiral, 1). Methylation at C5 gives 2,5-dimethylcyclopentanone: the cis isomer is meso (1) and the trans isomer exists as a pair of enantiomers (2). RDKit stereoisomer enumeration gives 1+3=4.