Question

A rule to check for a large number N being a prime number

(a) by dividing N by every even interger less than N/2

(b) by dividing N by every odd interger less than root(N)

(c) by dividing N by every even interger less than root(N)

(d) by dividing N by every interger less than N/2

This question was addressed to me in examination.

I'd like to ask this question from Principles of PRNG in chapter Pseudorandom Number Generation and Stream Ciphers and More Block Ciphers of Cryptograph & Network Security

Answer 1

The correct answer is (b) by dividing N by every odd interger less than root(N)

The best I can explain: A rule for checking if a number N is a prime is by dividing N by every odd interger less than root(N).