diff --git a/calculator.rb b/calculator.rb
new file mode 100644
index 0000000..e732e52
--- /dev/null
+++ b/calculator.rb
@@ -0,0 +1,61 @@
+# Calculator
+# by Sofia Kim(Queue)
+
+puts "Enter the the first number, operator and second number in order."
+
+a = gets.chomp
+b = gets.chomp
+c = gets.chomp
+
+# To validate if user inputs are valid numbers?
+def isNumber(str)
+  str == "0" || str.to_i != 0 #return boolean value / any string to i would return '0'. Therefore, if str.to_i is not '0' meaning that the str is actual number.
+end
+
+# To validate if the user input numbers include decimal points or not
+def hasDot(str)
+  str.include?(".")
+end
+
+# change data types of numbers (integer or float)
+def num_type(x)
+  if hasDot(x)
+    x.to_f
+  else
+    x.to_i
+  end
+end
+
+def calc(x, y, z)
+  # x = x.to_i; z = z.to_i
+  if isNumber(x) && isNumber(z)
+    x = num_type(x)
+    z = num_type(z)
+
+    ans = case y
+    when '+', 'add'
+      x + z
+    when '-', 'subtract'
+      x - z
+    when '*', 'multiply'
+      x * z
+    when '/', 'divide'
+      # The program handles divide when attempting to divide by zero
+      if z != 0
+        x / z
+      else puts "Please enter other than '0'"
+      end
+    when '%' , 'modulo'
+      x % z
+    when '**' , 'exponents'
+      x ** z
+    else
+      puts "Enter a valid operator"
+    end
+    # p ans
+    puts "#{x} #{y} #{z} = #{ans}"
+  else puts "Enter valid numbers"
+  end
+end
+
+calc(a,b,c)