diff --git a/constants.py b/constants.py
index c112449..d2f6168 100644
--- a/constants.py
+++ b/constants.py
@@ -13,6 +13,8 @@ PLUS = 'PLUS'
 MINUS = 'MINUS'
 MUL = 'MUL'
 DIV = 'DIV'
+IDIV = 'IDIV'
+MOD = 'MOD'
 POW = 'POW'
 SQRT = 'SQRT'
 
@@ -20,6 +22,8 @@ HEX = 'HEX'
 DEC = 'DEC'
 BIN = 'BIN'
 
+PI = 'PI'
+
 SWAP = 'SWAP'
 POP = 'POP'
 
diff --git a/interpreter.py b/interpreter.py
index b5ff42d..f2b4c05 100644
--- a/interpreter.py
+++ b/interpreter.py
@@ -8,7 +8,7 @@
 
 from constants import (
 	NUMBER, EOF,
-	PLUS, MINUS, MUL, DIV, POW, SQRT,
+	PLUS, MINUS, MUL, DIV, IDIV, MOD, POW, SQRT,
 	HEX, DEC, BIN,
 	SWAP, POP,
 )
@@ -53,7 +53,7 @@ class Interpreter:
 		while self.current_token.type is not EOF:
 			if self.current_token.type == NUMBER:
 				self.stack.append(self.current_token.value)
-			elif self.current_token.type in (PLUS, MINUS, MUL, DIV, POW):
+			elif self.current_token.type in (PLUS, MINUS, MUL, DIV, IDIV, MOD, POW):
 				self.evaluate_binary_operator(self.current_token)
 			elif self.current_token.type in (SQRT):
 				self.evaluate_unary_operator(self.current_token)
diff --git a/lexer.py b/lexer.py
index dca101f..5771210 100644
--- a/lexer.py
+++ b/lexer.py
@@ -12,8 +12,9 @@ import operator
 from token import Token
 from constants import (
 	NUMBER, EOF,
-	PLUS, MINUS, MUL, DIV, POW, SQRT,
+	PLUS, MINUS, MUL, DIV, IDIV, MOD, POW, SQRT,
 	HEX, DEC, BIN,
+	PI,
 	SWAP, POP,
 )
 
@@ -73,8 +74,15 @@ class Lexer():
 
 			elif self.current_char == '/':
 				self.advance()
+				if self.current_char == '/':
+					self.advance()
+					return Token(IDIV, operator.floordiv)
 				return Token(DIV, operator.truediv)
 
+			elif self.current_char == '%':
+				self.advance()
+				return Token(MOD, operator.mod)
+
 			elif self.current_char == '^':
 				self.advance()
 				return Token(POW, operator.pow)
@@ -94,6 +102,8 @@ class Lexer():
 					return Token(BIN, bin)
 				elif check.lower() == SQRT.lower():
 					return Token(SQRT, math.sqrt)
+				elif check.lower() == PI.lower():
+					return Token(NUMBER, math.pi)
 				elif check.lower() == SWAP.lower():
 					return Token(SWAP, text)
 				elif check.lower() == POP.lower():