diff --git a/calculator.rb b/calculator.rb
new file mode 100644
index 0000000..03f3ec0
--- /dev/null
+++ b/calculator.rb
@@ -0,0 +1,105 @@
+
+# FUNCTIONS
+
+# Boolean function on whether string input is a number
+def is_numeric(num)
+
+  if num.to_f.to_s == num || num.to_i.to_s == num
+    return true
+  else
+    return false
+  end
+
+end
+
+# Function to reprompt user if input is not valid
+def is_valid_numeric_input(order)
+
+  print "#{order} number >> "
+  num = gets.chomp
+
+  until is_numeric(num)
+    puts "Not valid number. Please try again."
+    print "#{order} number >> "
+    num = gets.chomp
+  end
+
+  return num
+end
+
+# Simplify to integer if possible
+def simplify_integer(num)
+  if num.to_i == num then
+    return num.to_i
+  else
+    return num
+  end
+end
+
+puts "\n\nWelcome to the calculator! Which operator do you want to use?"
+puts "\n\tadd (+)"
+puts "\tsubtract (-)"
+puts "\tmultiply (*)"
+puts "\tdivide (/)"
+puts "\texponify (^)"
+puts "\tmodulo (%)"
+
+print "\nPlease input name or symbol of operator >> "
+
+operators = ["add", "+", "subtract", "-", "multiply", "*", "divide", "/", "exponify", "^", "modulo", "%"]
+
+operator = gets.chomp.downcase
+until operators.include? operator
+  print "Not valid operation. Please try again. >> "
+  operator = gets.chomp
+end
+
+
+puts "What two numbers would you like to operate on respectively?"
+first_num = is_valid_numeric_input("first").to_f
+second_num = is_valid_numeric_input("second").to_f
+
+
+case operator
+  when "add", "+"
+    answer = first_num + second_num
+    symbol = "+"
+  when "subtract", "-"
+    answer = first_num - second_num
+    symbol = "-"
+  when "multiply", "*"
+    answer = first_num * second_num
+    symbol = "*"
+  when "divide", "/"
+
+    # Handle cases when trying to divide by zero
+    if second_num == 0 then
+
+      until is_numeric(second_num) && second_num.to_f != 0
+        puts "Please enter valid second number. (Cannot be zero)"
+        print "second number >> "
+        second_num = gets.chomp
+      end
+    end
+
+    second_num = second_num.to_f
+
+    answer = first_num / second_num
+    symbol = "/"
+
+  when "exponify", "^"
+    answer = first_num ** second_num
+    symbol = "^"
+
+  when "modulo", "%"
+    answer = first_num % second_num
+    symbol = "%"
+
+end
+
+# Simplify floats to integers if possible
+first = simplify_integer(first_num)
+second = simplify_integer(second_num)
+answer = simplify_integer(answer)
+
+puts "#{first} #{symbol} #{second} = #{answer}"