diff --git a/calc_engine.py b/calc_engine.py
index 8674efe..06727e1 100644
--- a/calc_engine.py
+++ b/calc_engine.py
@@ -3,6 +3,217 @@ import token
 def calculate_results(tokens):
 	
 	return 0
+	
+def handle_parenthesis(tokens, call_has_priority = False):
+	running_value = 0
+	previous_token = CToken("", token.TokenType.unknown)
+	
+	while True:
+		if len(tokens) == 0:
+			break
+		
+		current_token = tokens.pop()
+		
+		if current_token.type == token.TokenType.constant:
+			previous_token = current_token
+			
+		elif current_token == token.TokenType.exp_start:
+			running_value = handle_parenthesis(tokens)
+			
+		elif current_token.type == token.TokenType.add or current_token.type == token.TokenType.subtract:
+			look_ahead = tokens.pop()
+			
+			if look_ahead.type == token.TokenType.exp_start:
+				tmp = handle_parenthesis(tokens)
+				
+				if running_value == 0:
+					running_value = operate(previous_token.value, tmp, current_token.type)
+				else:
+					running_value = operate(running_value, tmp, current_token.type)
+				continue
+			
+			tokens.append(look_ahead)
+			tokens.append(current_token)
+			
+			if not previous_token.type == token.TokenType.unknown:
+				tokens.append(previous_token)
+			else:
+				tokens.append(CToken(running_value, token.TokenType.constant))
+				
+			running_value = handle_add_and_subtract(tokens)
+			#Set the previous_token to an invalid state so its not used by mistake.
+			previous_token.type = token.TokenType.unknown
+			
+		elif current_token.type == token.TokenType.power:
+			look_ahead = tokens.pop()
+			
+			if look_ahead.type == token.TokenType.exp_start:
+				power_of = handle_parenthesis(tokens, True)
+				
+				running_value = operate(previous_token.value, power_of, current_token.type)
+				#Set the previous_token to an invalid state so its not used by mistake.
+				previous_token.type = token.TokenType.unknown
+				continue
+			
+			running_value = operate(previous_token.value, look_ahead.value, current_token.type)
+			#Set the previous_token to an invalid state so its not used by mistake.
+			previous_token.type = token.TokenType.unknown
+			
+		elif current_token.type == token.TokenType.multiply or current_token.type == token.TokenType.divide:
+			look_ahead = peek_list(tokens)
+			
+			if look_ahead.type == token.TokenType.exp_start:
+				tokens.pop()
+				running_value = operate(previous_token.value, handle_parenthesis(tokens), current_token.type)
+				#Set the previous_token to an invalid state so its not used by mistake.
+				previous_token.type = token.TokenType.unknown
+				continue
+			
+			tokens.append(current_token)
+			
+			if not previous_token.type == token.TokenType.unknown:
+				tokens.append(previous_token)
+			else:
+				tokens.append(CToken(running_value, token.TokenType.constant))
+				
+			running_value = handle_multiply_and_division(tokens)
+			#Set the previous_token to an invalid state so its not used by mistake.
+			previous_token.type = token.TokenType.unknown
+			
+		elif current_token.type == token.TokenType.exp_end:
+			
+			if len(tokens) > 0 and peek_list(tokens).type == token.TokenType.power:
+				tokens.pop()
+				running_value = operate(running_value, tokens.pop().value, token.TokenType.power)
+				
+			if !caller_has_priority and len(tokens) > 0 and (peek_list(tokens).type == token.TokenType.multiply or peek_list(tokens).type == token.TokenType.divide):
+				operator = tokens.pop()
+				two_ahead = tokens.pop()
+				
+				if two_ahead.type == token.TokenType.exp_start:
+					running_value = operate(running_value, handle_parenthesis(tokens), operator.type)
+				else:
+					running_value = operate(running_value, two_ahead.value, operator.type)
+			
+			break
+
+	return running_value
+
+def handle_multiply_and_division(tokens):
+	running_value = 0
+	previous_token = CToken("", token.TokenType.unknown)
+	
+	while True:
+		if len(tokens) == 0:
+			break
+			
+		current_token = peek_list(tokens)
+		#check to see if we want to deal with this token here, making sure not to consume it just incase we 
+		#don't want to process it here.
+		if current_token.type != token.TokenType.multiply and current_token.type != token.TokenType.divide and current_token.type != token.TokenType.constant and current_token.type != token.TokenType.variable:
+			break
+		
+		#"Commit" the current token.
+		current_token = tokens.pop()
+		
+		if current_token.type == token.TokenType.constant:
+			previous_token = current_token
+			continue
+		
+		elif current_token.type == token.TokenType.multiply or current_token.type == token.TokenType.divide:
+			look_ahead = tokens.pop()
+			
+			if look_ahead.type == token.TokenType.exp_start:
+				tmp = handle_parenthesis(tokens, True)
+				
+				if running_value == 0:
+					running_value = operate(previous_token.value, tmp, current_token.type)
+				else:
+					running_value = operate(running_value, tmp, current_token.type)
+					
+				#Set the previous_token to an invalid state so its not used by mistake.
+				previous_token.type = token.TokenType.unknown
+				continue
+				
+			if look_ahead.type == token.TokenType.constant:
+				if running_value == 0:
+					running_value = operate(previous_token.value, look_ahead.value, current_token.type)
+				else:
+					running_value = operate(running_value, look_ahead.value, current_token.type)
+					
+			#Set the previous_token to an invalid state so its not used by mistake.
+			previous_token.type = token.TokenType.unknown
+			
+	return running_value
+	
+def handle_add_and_subtract(tokens):
+	running_value = 0
+	previous_token = CToken("", token.TokenType.unknown)
+	
+	while True:
+		if len(tokens) == 0:
+			break
+		
+		current_token = tokens.pop()
+		
+		if current_token.type == token.TokenType.constant:
+			previous_token = current_token
+			continue
+			
+		if current_token.type == token.TokenType.exp_end:
+			tokens.append(current_token)
+			break
+		
+		if current_token.type == token.TokenType.exp_start:
+			running_value = handle_parenthesis(tokens)
+			
+		elif current_token.type == token.TokenType.add or current_token.type == token.TokenType.subtract:
+			look_ahead = tokens.pop()
+			
+			if look_ahead.type == token.TokenType.exp_start:
+				tmp = handle_parenthesis(tokens)
+				
+				if running_value == 0:
+					running_value = operate(previous_token.value, tmp, current_token.type)
+				else:
+					running_value = operate(running_value, tmp, current_token.type)
+				previous_token.type = token.TokenType.unknown
+			
+			if len(tokens) > 0:
+				two_ahead = peek_list(tokens)
+				
+				if two_ahead.type == token.TokenType.multiply or two_ahead.type == token.TokenType.divide:
+					tokens.append(look_ahead)
+					
+					tmp = handle_multiply_and_division(tokens)
+
+					if running_value == 0:
+						running_value = operate(previous_token.value, tmp, current_token.type)
+					else:
+						running_value = operate(running_value, tmp, current_token.type)
+					previous_token.type = token.TokenType.unknown
+			
+			else:
+				if running_value == 0:
+					running_value = operate(previous_token.value, look_ahead.value, current_token.type)
+				else:
+					running_value = operate(running_value, look_ahead.value, current_token.type)
+				previous_token.type = token.TokenType.unknown
+			
+		elif current_token.type == token.TokenType.multiply or current_token.type == token.TokenType.divide:
+			tokens.append(current_token)
+			
+			if previous_token.type != token.TokenType.unknown:
+				tokens.append(previous_token)
+			else:
+				tokens.append(CToken(running_value, token.TokenType.constant))
+			
+			running_value = handle_multiply_and_division(tokens)
+			
+			previous_token.type = token.TokenType.unknown
+			
+	return running_value
+				
 
 def peek_list(tokens):
     if tokens:
diff --git a/tokenizer.py b/tokenizer.py
index 485f9a8..88385b3 100644
--- a/tokenizer.py
+++ b/tokenizer.py
@@ -1,10 +1,10 @@
 import token
 
 def get_tokens_from_expression_string(expression_string):
-	"""
-	Takes user input of an actuarial formula and parses the formula to id its components.
-	:return: tokens (List of objects of CToken class).
-	"""
+
+	#Takes user input of an actuarial formula and parses the formula to id its components.
+	#:return: tokens (List of objects of CToken class).
+	
 	tokens = []  # List of objects of CToken class
 	tmp = ""
 	parsing_number = False