Number-System
Number System: Divisibility, HCF–LCM and Remainders
CSAT number system with worked examples — divisibility rules, counting factors, HCF and LCM applications, …
Number System
CSAT number system for UPSC Prelims Paper II — divisibility rules, factors, HCF and LCM, remainders, unit …
Number System — Practice Questions
CSAT-pattern number system practice — divisibility by 11, HCF–LCM pairs, power remainders, traffic-light LCM, …
Number System — Quick Revision
One-page CSAT revision of the number system: divisibility rules, factor counting, HCF–LCM uses, remainder and …