diff --git a/wk1_calc.rb b/wk1_calc.rb
new file mode 100644
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--- /dev/null
+++ b/wk1_calc.rb
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+#Calculator Exercise
+#command line interface that allows a user to perform simple arithmetic
+
+puts "This calculator will perform simple arithmetic on two numbers, using either addition, subtraction, multiplication, or division."
+puts
+
+print "What is the first number? "
+num_one = gets.chomp.to_f
+
+print "What is the second number? "
+num_two = gets.chomp.to_f
+
+print "Which operation would you like performed? "
+command = gets.chomp.upcase.to_s
+
+until ["ADD", "+", "SUBTRACT", "-", "MULTIPLY", "*", "DIVIDE", "/"].include?(command)
+  puts "You did not enter an available operation. Please try again."
+  command = gets.chomp.upcase.to_s
+end
+
+puts command
+
+case command
+  when "ADD", "+"
+    puts "We're adding numbers"
+    puts num_one + num_two
+  when "SUBTRACT", "-"
+    puts "We're subtracting numbers"
+      puts num_one - num_two
+  when "MULTIPLY", "*"
+    puts "We're multiplying numbers"
+    puts num_one * num_two
+  when "DIVIDE", "/"
+    puts "We're dividing numbers"
+    puts num_one / num_two
+  else
+    puts "You did not enter an available operation. Please try again."
+end
+
+
+#Bike rack for future enhancements
+#av_commands = ["ADD", "+", "SUBTRACT", "-", "MULTIPLY", "*", "DIVIDE", "/"]