diff --git a/2020/Python/day18.py b/2020/Python/day18.py
new file mode 100644
index 0000000..9bc6ff2
--- /dev/null
+++ b/2020/Python/day18.py
@@ -0,0 +1,171 @@
+from enum import Enum
+from typing import Union
+
+
+class TokenType(Enum):
+    Number = 0
+    Op1 = 1
+    Op2 = 2
+    Op3 = 3
+    LParen = 8
+    RParen = 9
+    Invalid = 10
+
+
+class Token:
+    def __init__(self, token_type: TokenType, data: Union[float, str, None]):
+        self.token_type = token_type
+        self.data = data
+
+    def clone(self):
+        return Token(self.token_type, self.data)
+
+    def __str__(self):
+        return f"({self.token_type}:{self.data})"
+
+
+def tokenize_string(string: str) -> list[Token]:
+    token_list = []
+    for char in string:
+        if char.isdigit() or char == '.':
+            token_list.append(Token(TokenType.Number, char))
+        elif char == '-':
+            if not token_list or token_list[-1].token_type not in [TokenType.Number, TokenType.RParen]:
+                token_list.append(Token(TokenType.Number, char))
+            else:
+                token_list.append(Token(TokenType.Op1, char))
+        elif char in ['*']:  # Changes to this place change operation precedence
+            token_list.append(Token(TokenType.Op1, char))
+        elif char in ['+']:
+            token_list.append(Token(TokenType.Op2, char))
+        elif char == '^':
+            token_list.append(Token(TokenType.Op3, char))
+        elif char == '(':
+            token_list.append(Token(TokenType.LParen, None))
+        elif char == ')':
+            token_list.append(Token(TokenType.RParen, None))
+        else:
+            token_list.append(Token(TokenType.Invalid, None))
+    return token_list
+
+
+def simplify_token_list(tokens: list[Token]) -> list[Token]:
+    simplified_list = []
+
+    if len(tokens) != 0:
+        simplified_list.append(tokens[0].clone())
+        for i in range(1, len(tokens)):
+            if tokens[i].token_type == TokenType.Number and simplified_list[-1].token_type == TokenType.Number:
+                simplified_list[-1].data += tokens[i].data
+            else:
+                simplified_list.append(tokens[i].clone())
+
+    for token in simplified_list:
+        if token.token_type == TokenType.Number:
+            if token.data in ['.', '-']:
+                token.data = None
+                token.token_type = TokenType.Invalid
+            elif token.data[:1] == '.':
+                token.data = "0" + token.data
+            elif token.data[-1:] == '.':
+                token.data += '0'
+
+            number_of_dots = 0
+            for char in str(token.data):
+                if char == '.':
+                    number_of_dots += 1
+            if number_of_dots > 1:
+                token.data = None
+                token.token_type = TokenType.Invalid
+
+    return simplified_list
+
+
+def generate_rpn(token_list: list[Token]) -> list[Token]:
+    stack = []
+    output = []
+
+    for token in token_list:
+
+        if token.token_type in [TokenType.Number, TokenType.Invalid]:
+            output.append(token)
+
+        elif token.token_type == TokenType.LParen:
+            stack.append(token)
+
+        elif token.token_type == TokenType.RParen:
+            if not stack:
+                return [Token(TokenType.Invalid, None)]
+            operator = stack.pop()
+            while not operator.token_type == TokenType.LParen:
+                output.append(operator)
+                if not stack:
+                    return [Token(TokenType.Invalid, None)]
+                operator = stack.pop()
+
+        else:  # Correct but linter says it's not
+            while stack and 1 <= stack[-1].token_type.value <= 3 and token.token_type.value <= stack[-1].token_type.value:
+                output.append(stack.pop())
+            stack.append(token)
+
+    while stack:
+        output.append(stack.pop())
+
+    return output
+
+
+def solve_rpn(rpn_tokens: list[Token]) -> (bool, Union[int, float]):
+    stack: list[Union[int, float]] = []
+    for token in rpn_tokens:
+        if token.token_type == TokenType.Number:
+            stack.append(float(token.data) if '.' in token.data else int(token.data))
+        else:
+            if len(stack) < 2:
+                return False, 0
+            b = stack.pop()
+            a = stack.pop()
+            if token.data == '+':
+                stack.append(a+b)
+            elif token.data == '-':
+                stack.append(a-b)
+            elif token.data == '*':
+                stack.append(a*b)
+            elif token.data == '/':
+                if b == 0:
+                    return False, 0
+                stack.append(a/b)
+            elif token.data == '^':
+                stack.append(a**b)
+            else:
+                return False, 0
+    if len(stack) == 1:
+        return True, stack[0]
+    else:
+        return False, 0
+
+
+def solve(string: str) -> (bool, float):
+    tokenized = tokenize_string(string.replace(" ", ""))
+    simplified = simplify_token_list(tokenized)
+    rpned = generate_rpn(simplified)
+    return solve_rpn(rpned)
+
+
+def parse_data() -> list[str]:
+    data = []
+    with open("input.txt") as file:
+        for line in file:
+            data.append(line.rstrip())
+    return data
+
+
+def solve_p1_p2(data: list[str]) -> int:
+    sum_res = 0
+    for calc in data:
+        succ, res = solve(calc)
+        sum_res += res
+    return sum_res
+
+
+DATA = parse_data()
+print(solve_p1_p2(DATA))