diff --git a/calculator.rb b/calculator.rb
new file mode 100644
index 0000000..934743f
--- /dev/null
+++ b/calculator.rb
@@ -0,0 +1,66 @@
+# method defining which operator user chooses
+def operatorchoice(operator)
+  case operator
+  when "add", "+", "addition", "adding", "add(+)"
+    return "+"
+  when "subtract", "-", "subtraction", "subtracting", "subtract(-)"
+    return "-"
+  when "multiply", "*", "multiplication", "multiplying", "multiply(*)"
+    return "*"
+  when "divide", "/", "division", "dividing", "divide(/)"
+    return "/"
+  else
+    return "invalid"
+  end
+end
+
+
+# introduction to user and prompt choice of operator
+puts "Welcome to the Calculator! Which operator would you like to use?
+add(+)
+subtract(-)
+multiply(*)
+divide(/)
+Please choose one operator(name OR symbol):"
+
+operator_entered = gets.chomp
+operator_active = operatorchoice(operator_entered)
+while operator_active == "invalid"
+  puts "That is not a valid operator. Please choose again one operator(name or symbol):"
+  operator_entered = gets.chomp
+  operator_active = operatorchoice(operator_entered)
+end
+
+puts "Please enter number 1: "
+  ans1 = gets.chomp
+  num1 = ans1.to_f
+  until ans1.to_i.to_s == ans1 || ans1.to_f.to_s == ans1
+    puts "Please re-enter number 1: "
+    ans1 = gets.chomp
+    num1 = ans1.to_f
+  end
+
+puts "Please enter number 2"
+  ans2 = gets.chomp
+  num2 = ans2.to_f
+  until ans2.to_i.to_s == ans2 || ans2.to_f.to_s == ans2
+    puts "Please re-enter number 2: "
+    ans2 = gets.chomp
+    num2 = ans2.to_f
+  end
+
+# defining method for calculation
+def calculator(operator_active, num1, num2)
+  case operator_active
+    when "+"
+      return num1 + num2
+    when "-"
+      return num1 - num2
+    when "*"
+      return num1 * num2
+    when "/"
+        return num1 / num2
+  end
+end
+
+puts "Answer: #{num1} #{operator_active} #{num2} = #{calculator(operator_active, num1, num2)}"