Heyy guyz and Galz here'z an easy way to learn the table of 7 primitive unit cells and their possible variations as centered unit cells

                 Cubic                                               A (aa)         (all sides equal)                a=b=c

                 Hexagonal                                      O (o)          (only one side equal)          a=b..not equal c

                 Monohedral                                     N (na)         (None equal)                     a..not equal..b...not equal..c

                 Orthorhombic                                N (na)

                 Rombohedral                                 A (aa)

                 Tetrahedral                                      O (o)

                  Triclinic                                             N (na)

CHM-------stands for Chemistry

OR--------stands for Organic

TT---------stands for tantan

So combining these we get CHeMistry ORganic  TanaTan

On the other side

A----- aa                                                                                A- All sides equal

O----o                                                                                     O- Only one side equal

N---- naa                                                                               N- None equal

Combining we get Aa O Na Na Aa O Na