diff --git a/src/LispEnv.hs b/src/LispEnv.hs
index 1a8675d..27cbd5c 100644
--- a/src/LispEnv.hs
+++ b/src/LispEnv.hs
@@ -62,9 +62,9 @@ evalEq [Expr exp, other] env = do
     evalEq [Atom first, other] nEnv
 evalEq [other, Expr exp] env = do
     (first, nEnv) <- evalS exp env
-    evalEq [Atom first, other] nEnv
+    evalEq [other, Atom first] nEnv
 evalEq [Atom (AQuote quoted), other] env = evalEq [Atom quoted, other] env
-evalEq [other, Atom (AQuote quoted)] env = evalEq [Atom quoted, other] env
+evalEq [other, Atom (AQuote quoted)] env = evalEq [other, Atom quoted] env
 evalEq _ _ = Left "**Error: Invalid arguments in eq?**"
 
 evalAtom :: [Statement] -> LispEnv -> Either String (Atom, LispEnv)
diff --git a/src/Maths.hs b/src/Maths.hs
index b7d3556..a2fe35b 100644
--- a/src/Maths.hs
+++ b/src/Maths.hs
@@ -6,7 +6,9 @@ mathEnv :: LispEnv
 mathEnv = [
         ("+", ABuiltin "+" evalPlus),
         ("-", ABuiltin "-" evalMinus),
-        ("*", ABuiltin "*" evalMult)
+        ("*", ABuiltin "*" evalMult),
+        ("div", ABuiltin "div" evalDiv),
+        ("mod", ABuiltin "mod" evalMod)
     ]
 
 evalPlus :: [Statement] -> LispEnv -> Either String (Atom, LispEnv)
@@ -44,3 +46,30 @@ evalMult (x:xs) env = do
          (AInt f, AFloat s) -> Right (AFloat $ fromIntegral f * s, nnEnv)
          (value, _) -> Left $ "**Error: \"" ++ show value ++ "\" is not a number **"
 evalMult [] env = Right (AInt 1, env)
+
+evalDiv :: [Statement] -> LispEnv -> Either String (Atom, LispEnv)
+evalDiv [_, Atom (AInt 0)] env = Left "**Error: Division by 0 is undefined.**"
+evalDiv [_, Atom (AFloat 0)] env = Left "**Error: Division by 0 is undefined.**"
+evalDiv [Atom (AInt f), Atom (AInt s)] env = Right (AInt (f `div` s), env)
+evalDiv [Atom (AFloat f), Atom (AFloat s)] env = Right (AFloat (f / s), env)
+evalDiv [Atom (AFloat f), Atom (AInt s)] env = Right (AFloat (f / fromIntegral s), env)
+evalDiv [Atom (AInt f), Atom (AFloat s)] env = Right (AFloat (fromIntegral f / s), env)
+evalDiv [Expr expr, other] env = do
+    (res, nEnv) <- evalS expr env
+    evalDiv [Atom res, other] nEnv
+evalDiv [other, Expr expr] env = do
+    (res, nEnv) <- evalS expr env
+    evalDiv [other, Atom res] nEnv
+evalDiv _ _ = Left "**Error: Invalid arguments in div.**"
+
+evalMod :: [Statement] -> LispEnv -> Either String (Atom, LispEnv)
+evalMod [_, Atom (AInt 0)] env = Left "**Error: mod by 0 is undefined.**"
+evalMod [_, Atom (AFloat 0)] env = Left "**Error: mod by 0 is undefined.**"
+evalMod [Atom (AInt f), Atom (AInt s)] env = Right (AInt (f `mod` s), env)
+evalMod [Expr expr, other] env = do
+    (res, nEnv) <- evalS expr env
+    evalMod [Atom res, other] nEnv
+evalMod [other, Expr expr] env = do
+    (res, nEnv) <- evalS expr env
+    evalMod [other, Atom res] nEnv
+evalMod _ _ = Left "**Error: Invalid arguments in mod.**"
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