[Ruby] Multi-use Calculator - Printable Version

Code:
#SciCalc by Nightc||ed, ©2015
@pi = Math::PI
@e = Math::E
def dir
	def get_int_values_a
		[gets, gets].map{ |s| s.chomp.to_i }
	end
	def get_int_values_b
		[gets].map{ |s| s.chomp.to_i }
	end
	system "cls"
	puts """	Directory	
[1] References
[2] Basic calculator
[3] Advanced calculator
[4] Trig/Calc"""
	sect = gets.chomp
	system "cls"
	case sect
		when "1"
			puts """	References	
	[to go back to the directory, hit enter]
Pi: #{@pi}

e:  #{@e}

Perfect squares, to 12x:
1, 4, 9, 16, 25, 36, 49,
64, 81, 100, 121, 144

Perfect cubes, to 12x:
1, 8, 27, 64, 125, 216,
343, 512, 729, 1000,
1331, 1728

Prime numbers, to 100:
1, 2, 3, 5, 7, 11, 13,
17, 19, 23, 29, 31, 37,
41, 43, 47, 53, 59, 61,
67, 71, 73, 79, 83, 89,
97
"""
		when "2"
			puts "Would you like to [1]add, [2]multiply, [3]subtract or [4]divide?"
			response = gets.chomp
			system "cls"
			case response
				when "1"
					puts "Which numbers would you like to add (first value, enter, second value)?"
  					operator = :+
				when "2"
					puts "Which numbers would you like to subtract (first value, enter, second value)?"
					operator = :-
				when "3"
					puts "Which numbers would you like to multiply (first value, enter, second value)?"
					operator = :*
				when "4"
					puts "Which numbers would you like to divide (first value, enter, second value)?"
					operator = :/
			end
			answer = get_int_values_a.inject(operator)
			puts "The answer is... #{answer}"
		when "3"
			puts "would you like to use [1]modulus, [2]exponent, [3]square root or [4]cube root?"
			response = gets.chomp
			system "cls"
			case response
				when "1"
					puts "Which numbers would you like to use (first value, enter, second value)?" #if anyone knows the use term for modulus, lmk
					operator = :%
					answer = get_int_values_a.inject(operator)
					puts "The answer is... #{answer}"
				when "2"
					puts "Which numbers would you like to use (first value, enter, second value)?"
					operator = :**
					answer = get_int_values_a.inject(operator)
					puts "The answer is... #{answer}"
				when "3"
					puts "What number would you like to root?"
					a = gets.to_i
					a = Math.sqrt(a)
					puts "The answer is... #{a}"					
				when "4"
					puts "What number would you like to root?"
					a = gets.to_i
					a = (Math.exp(Math.log(a.to_i)/3.to_i)).round
					puts "The answer is... #{a}"
			end
		when "4"
			puts "WIP"
	end
	kden = gets.chomp
	dir
end
dir