diff --git a/cli-calculator b/cli-calculator
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+# BASELINE
+
+# The program should ask the user for an operation (string or numeric symbol) and two numbers.
+
+# PRIMARY REQUIREMENTS
+
+# The program should use the input operation and two numbers to provide the result of applying the operation to the two numbers.
+
+
+def calculate(number1, number2, operation)
+     case operation
+          when "add", "+"
+           puts "Your end result is #{number1} + #{number2} = #{number1 + number2}."
+          when "subtract", "-"
+           puts "Your end result is #{number1} - #{number2} = #{number1 - number2}."
+          when "multiply", "*"
+           puts "Your end result is #{number1} * #{number2} = #{number1 * number2}."
+          when "divide", "/"
+           puts "Your end result is #{number1} / #{number2} = #{number1 / number2}."
+     end
+end
+
+numbers = Array.new
+print "What sort of calculation would you like to do ( add , subtract , multiply or divide )? "
+
+operations = %w[add + subtract - multiply * divide /]
+
+operation = gets.chomp
+
+until operations.include?(operation)
+     puts "You've four options. Pick one. "
+     puts "( add , subtract , multiply or divide )"
+     operation = gets.chomp.downcase
+end
+
+puts "What two whole numbers (1 - 100) would you like to #{operation}? "
+
+2.times do | input |
+     print "##{input + 1}: "
+     number = gets.chomp.to_i
+
+     until (1..100).to_a.include?(number)
+          puts "1 through 100. Pick one. "
+          print "##{input + 1}: "
+          number = gets.chomp.to_i
+     end
+
+     numbers << number
+end
+
+number1 = numbers[0]
+number2 = numbers[1]
+
+calculate(number1, number2, operation)
+
+puts "\n"
+
+# TEST & VERIFY
+# ✓ The program adds numbers with both add and +.
+# ✓ The program subtracts numbers with both subtract and -.
+# ✓ The program multiply numbers with both multiply and *.
+# ✓ The program divides numbers with both divide and /.
+# ✓ The program handles divide when attempting to divide by zero.
+# ✓ The program handles erroneous input. For example the user might enter clown when asked to enter a number.
+# ✓ The program also needs to handle erroneous operators.
+
+#OPTIONAL ENHANCEMENTS
+
+# ✓ Print out the formula in addition to the result, i.e. 2 + 2 = 4
+# (Pass) Add support for computing exponents (2^4 = 2 * 2 * 2 * 2 = 16).
+# (Pass) Add support for the modulo operator (10 % 3 = 1).
+# ✓ Gracefully handle unexpected user input:
+# (Pass) What happens if the user input is nil (i.e., the user just pressed enter)?
+# ✓ What happens if the user tries to add hotdog to elephant?
+
+
+def calculate( number1, number2, operation )
+     case operation
+          when "add", "+"
+           puts "Your end result is #{number1} + #{number2} = #{number1 + number2}."
+          when "subtract", "-"
+           puts "Your end result is #{number1} - #{number2} = #{number1 - number2}."
+          when "multiply", "*"
+           puts "Your end result is #{number1} * #{number2} = #{number1 * number2}."
+          when "divide", "/"
+           puts "Your end result is #{number1} / #{number2} = #{number1 / number2}."
+     end
+end
+
+numbers = Array.new
+print "What sort of calculation would you like to do ( add , subtract , multiply or divide )? "
+
+operations = %w[add + subtract - multiply * divide /]
+
+operation = gets.chomp
+
+until operations.include?(operation)
+     print "Add. Subtract. Multiply. Or divide. You've four options. Pick one: "
+     operation = gets.chomp.downcase
+end
+
+puts "What two numbers (1 - 100) would you like to #{operation}? "
+
+2.times do | input |
+     print "##{input + 1}: "
+     number = gets.chomp.to_f
+
+     until number < 100 && number > 0
+          print "(Sigh.) 1 through 100. Pick one: "
+          number = gets.chomp.to_f
+     end
+
+     if number - number.floor > 0
+          numbers << number
+
+          elsif number - number.floor == 0
+               numbers << number.to_i
+     end
+end
+
+number1 = numbers[0]
+number2 = numbers[1]
+
+calculate(number1, number2, operation)
+
+puts "\n"
+
+# ✓ Make your program know when it needs to return an integer versus a float.
+
+# TODO
+
+# Add support for parentheticals, i.e. 10 / (5 + 5) = 1.