Pseudocode for naive primality test:

boolean naive_primality_test
	input: an positive integer n
	output: true if n is a prime number and false otherwise

	a = 2 
	while a < n
		// test if n is divisible by a
		// (the symbol % means modular reduction and you may assume
			that it is implemented using a division, a multiplication,
			and a subtraction)
		if 0 == n % a
			return false
		a += 1
	return true