I think taxi companies or LTA do provide these on those self service counter ..... Go get one and study a bit , no need study by hard lar . Just take and anaylse why A01 ? Why E01 ? Why C01 ? And while glancing , visualise those areas ... Like A01 Lucky Plaza , next ? A02 Paragon , A03 Mt E , etc .... the A's keep going down Orchard Road . Then Why B ? Boundary of Bugis , so u visualised the Bugis boundaries . Where C ? And so on .... This lesson is million dollar lesson , hahahahahah