Number System Questions with Solutions

The number system is the foundation of quantitative aptitude. It covers the different types of numbers (natural numbers, whole numbers, integers, rational and irrational numbers, primes and composites) and the rules that govern them. Exam questions test divisibility rules, unit digits of large powers, remainders, factors and multiples, HCF and LCM, and the number of trailing zeros in a factorial. Most of these questions can be solved in under a minute once you know the pattern. Unit digits repeat in cycles of four, and divisibility by 11 depends on the difference between the sums of alternate digits. Number properties also appear inside questions on simplification, averages and series, so strong basics here save time across the whole quant section. Practise the questions below to build speed with divisibility, remainders, unit digits and HCF-LCM. Every question has a step-by-step solution and, where possible, a shortcut method.