diff --git a/calculator.rb b/calculator.rb
new file mode 100644
index 0000000..1cd930c
--- /dev/null
+++ b/calculator.rb
@@ -0,0 +1,102 @@
+def match_number(num) # creating a method to be used for both user number inputs
+  until num.match(/^\-?\d*\.?\d*$/) && !num.empty?
+    if !num.match(/^\-?\d*\.?\d*$/)
+      print "Invalid input. Please enter a number: "
+      num = gets.chomp
+    end
+    if num.empty?
+      print "No number inputted. Please enter a number: "
+      num = gets.chomp
+    end
+  end
+end
+
+def input_conversion(input) # to handle both float or integer input
+  if input.include?(".")
+    input.to_f
+  else
+    input.to_i
+  end
+end
+
+possible_ops = {
+  add: ["add", "+", "addition"],
+  subtract: ["subtract", "-", "subtraction"],
+  multiply: ["multiply", "*", "multiplication"],
+  divide: ["divide", "/", "division"],
+  exponent: ["exponent", "^"],
+  modulo: ["modulo", "%"]}
+
+puts "Please enter a mathematical operation and two numbers. \n \n"
+print "First Number: "
+input1 = gets.chomp
+match_number(input1)
+input1 = input_conversion(input1)
+
+print "Second Number: "
+input2 = gets.chomp
+match_number(input2)
+input2 = input_conversion(input2)
+
+print "Operation: "
+opInput = gets.chomp
+until possible_ops.values.flatten.include?(opInput) # checking if the input is included in the possible operations
+  print "Invalid operation. Try again: "
+  opInput = gets.chomp
+end
+
+def add(num1, num2)
+  answer = num1 + num2
+  return "#{num1} + #{num2} = #{answer}"
+end
+
+def subtract(num1, num2)
+  answer = num1 - num2
+  return "#{num1} - #{num2} = #{answer}"
+end
+
+def multiply(num1, num2)
+  answer = num1 * num2
+  return "#{num1} * #{num2} = #{answer}"
+end
+
+def divide(num1, num2)
+  until num2 != 0
+    puts "Invalid entry. Can't divide by zero."
+    print "Please choose another number: "
+    num2 = gets.chomp
+    match_number(num2)
+    num2 = input_conversion(num2)
+  end
+  answer = num1 / num2
+  return "#{num1} / #{num2} = #{answer}"
+end
+
+def exponent(num1, num2)
+  answer = num1 ** num2
+  return "#{num1} ^ #{num2} = #{answer}"
+end
+
+def modulo(num1, num2)
+  answer = num1 % num2
+  return "#{num1} % #{num2} = #{answer}"
+end
+
+case
+when possible_ops[:add].include?(opInput)
+  total = add(input1, input2)
+when possible_ops[:subtract].include?(opInput)
+  total = subtract(input1, input2)
+when possible_ops[:multiply].include?(opInput)
+  total = multiply(input1, input2)
+when possible_ops[:divide].include?(opInput)
+  total = divide(input1, input2)
+when possible_ops[:exponent].include?(opInput)
+  total = exponent(input1, input2)
+when possible_ops[:modulo].include?(opInput)
+  total = modulo(input1, input2)
+else
+  puts "That operation is not valid."
+end
+
+puts total