Arithmetic & Number System: 3 MCQs with Explanations

A prime number is a natural number greater than 1 with no positive divisors other than 1 and itself. 2 is the smallest and only even prime number.

The sum of the first n natural numbers is given by n(n+1)/2. For n=5, the sum is (5*6)/2 = 30/2 = 15.

Irrational numbers cannot be expressed as a simple fraction (p/q). π (pi) is a classic example, as its decimal representation is non-repeating and non-terminating.