diff --git a/packages/lists/lists.grnd b/packages/lists/lists.grnd
index cd60284..faabc99 100644
--- a/packages/lists/lists.grnd
+++ b/packages/lists/lists.grnd
@@ -10,11 +10,31 @@ fun -string !ltos -list &inlist
         add $ans $store &ans
         add $idx 1 &idx
         equal $idx $listlen &store
-        if $store %trueend
+        if $store %end
         add $ans ", " &ans
         jump %stdoutloop
 
-    @trueend
+    @end
     add $ans "]" &ans
     return $ans
+endfun
+
+fun -list !listremove -list &input
+    set &idx 0
+    getlistsize *input &endidx
+    subtract $endidx 1 &endidx
+    setlist *ans
+
+    @loop
+        equal $idx $endidx &store
+        if $store %return
+
+        getlistat *input $idx &store
+        listappend *ans $store
+
+        add $idx 1 &idx
+        jump %loop
+
+    @return
+    return *ans
 endfun
\ No newline at end of file
diff --git a/packages/lists/readme.md b/packages/lists/readme.md
index 9a9640d..a869070 100644
--- a/packages/lists/readme.md
+++ b/packages/lists/readme.md
@@ -8,4 +8,8 @@ Please note that you cannot copy a single function from the package, as some fun
 
 ### fun -string !ltos -list &inlist
 
-Converts a list to a string, in the format [$item1, $item2, $item3, ...] (no prerequisites).
\ No newline at end of file
+Converts a list to a string, in the format [$item1, $item2, $item3, ...] (no prerequisites).
+
+### fun -list !listremove -list &input
+
+Removes the last item from a list.
\ No newline at end of file
diff --git a/packages/math/math.grnd b/packages/math/math.grnd
index 1842272..7fbbfb2 100644
--- a/packages/math/math.grnd
+++ b/packages/math/math.grnd
@@ -453,4 +453,132 @@ fun -double !ln -double &in
 
     @error
     error "Cannot find ln of a non-positive double" "mathError"
+endfun
+
+fun -double !rpn -list &rpn
+    use "lists"
+
+    # List format: [3, 2, 4, '+', '-'] returns -3
+    setlist *stack
+    getlistsize *rpn &len
+    set &idx 0
+
+    @loop
+        equal $idx $len &store
+        if $store %return
+
+        # If type is a number, add it to the stack
+        getlistat *rpn $idx &store
+        gettype $store &store
+        equal $store "double" &bool
+        if $bool %pushstack
+        equal $store "int" &bool
+        if $bool %pushstack
+
+        getlistat *rpn $idx &store
+
+        equal $store '+' &bool
+        if $bool %add
+
+        equal $store '-' &bool
+        if $bool %subtract
+
+        equal $store '*' &bool
+        if $bool %multiply
+
+        equal $store '/' &bool
+        if $bool %divide
+
+        jump %increment
+
+        @add
+            getlistsize *stack &store
+            subtract $store 2 &store
+            getlistat *stack $store &list1
+
+            add $store 1 &store
+            getlistat *stack $store &list2
+
+            add $list1 $list2 &list1
+
+            subtract $store 1 &store
+            setlistat *stack $store $list1
+
+            pusharg *stack
+            call !packages/lists/lists:listremove &stack
+
+            jump %increment
+
+        @subtract
+            getlistsize *stack &store
+            subtract $store 2 &store
+            getlistat *stack $store &list1
+
+            add $store 1 &store
+            getlistat *stack $store &list2
+
+            subtract $list1 $list2 &list1
+
+            subtract $store 1 &store
+            setlistat *stack $store $list1
+
+            pusharg *stack
+            call !packages/lists/lists:listremove &stack
+
+            jump %increment
+
+        @multiply
+            getlistsize *stack &store
+            subtract $store 2 &store
+            getlistat *stack $store &list1
+
+            add $store 1 &store
+            getlistat *stack $store &list2
+
+            multiply $list1 $list2 &list1
+
+            subtract $store 1 &store
+            setlistat *stack $store $list1
+
+            pusharg *stack
+            call !packages/lists/lists:listremove &stack
+
+            jump %increment
+
+        @divide
+            getlistsize *stack &store
+            subtract $store 2 &store
+            getlistat *stack $store &list1
+
+            add $store 1 &store
+            getlistat *stack $store &list2
+
+            divide $list1 $list2 &list1
+
+            subtract $store 1 &store
+            setlistat *stack $store $list1
+
+            pusharg *stack
+            call !packages/lists/lists:listremove &stack
+
+            jump %increment
+
+        @pushstack
+        getlistat *rpn $idx &store
+        listappend *stack $store
+        jump %increment
+
+        @increment
+        add $idx 1 &idx
+        jump %loop
+
+    @return
+    getlistsize *stack &store
+    greater $store 1 &store
+    if $store %error
+    getlistat *stack 0 &store
+    return $store
+
+    @error
+    error "Stack for !fpn has multiple contents" "rangeError"
 endfun
\ No newline at end of file
diff --git a/packages/math/readme.md b/packages/math/readme.md
index ab17b8a..6795691 100644
--- a/packages/math/readme.md
+++ b/packages/math/readme.md
@@ -6,70 +6,52 @@ Please note that you cannot copy a single function from the package, as some fun
 
 ## Functions
 
-### fun -double !sin -double &input
+# Trigonometry
 
-Gets the sin of input.
+fun -double !sin -double &input: Gets the sin of input.
 
-### fun -double !cos -double &input
+fun -double !cos -double &input: Gets the cos of input.
 
-Gets the cos of input.
+fun -double !tan -double &input: Gets the tan of input.
 
-### fun -double !tan -double &input
+fun -double !asin -double &input: Finds the angle *x* in the range [-pi/2, pi/2] such that sin(x) equals the input.
 
-Gets the tan of input.
+fun -double !acos -double &input: Finds the angle *x* in the range [0, pi] such that cos(x) equals the input.
 
-### fun -double !asin -double &input
+fun -double !atan -double &input: Finds the angle *x* in the range [-pi/2, pi/2] such that tan(x) equals the input.
 
-Finds the angle *x* in the range [-pi/2, pi/2] such that sin(x) equals the input.
+fun -double !atan2 -double &y -double &x: Finds the angle in the range (-pi, pi] between the positive x axis and the point (x,y). This is equivalent to atan(y/x) for positive values of x.
 
-### fun -double !acos -double &input
+# Exponents and Logarithms
 
-Finds the angle *x* in the range [0, pi] such that cos(x) equals the input.
+fun -double !intexp -double &base -int &power: Returns base^power, for positive integer values of power. Returns 1 if power is non-positive (and thus is inaccurate for negative values of power).
 
-### fun -double !atan -double &input
+fun -double !exp -double &input: Finds exp($input), where exp(x)=e^x; e is Euler's number = 2.718281828...
 
-Finds the angle *x* in the range [-pi/2, pi/2] such that tan(x) equals the input.
+fun -double !ln -double &in: Finds the natural log (log_e) of $input, i.e. finds x such that e^x = $input; e is Euler's number = 2.718281828...
 
-### fun -double !atan2 -double &y -double &x
+fun -double !sqrt -double &input: Returns the positive value *x* that satisfies x^2 = input. Throws an error if input is negative.
 
-Finds the angle in the range (-pi, pi] between the positive x axis and the point (x,y). This is equivalent to atan(y/x) for positive values of x.
+# Integer Operations
 
-### fun -double !intexp -double &base -int &power
+fun -double !mod -double &in -double &modulus: Returns *n* such that *n* is congruent to the input modulo $modulus, where *n* is at least 0 and less than $modulus.
 
-Returns base^power, for positive integer values of power. Returns 1 if power is non-positive (and thus is inaccurate for negative values of power).
+fun -double !abs -double &in: Returns the absolute value of the input.
 
-### fun -double !exp -double &input
+fun -int !factorial -int &in: Returns the factorial of the input.
 
-Finds exp($input), where exp(x)=e^x, e is Euler's number = 2.718281828...
+# Constants
 
-### fun -double !ln -double &in
+fun -double !pi: Returns pi to the maximum accuracy that doubles can store.
 
-Finds the natural log (log_e) of $input, i.e. finds x such that e^x = $input, e is Euler's number = 2.718281828...
+fun -double !e: Returns e to the maximum accuracy that doubles can store.
 
-### fun -double !sqrt -double &input
+# Misc
 
-Returns the positive value *x* that satisfies x^2 = input. Throws an error if input is negative.
+fun -double !random -int &seed: Gets a random double in the domain [0,1), using a LCG. A seed is required.
 
-### fun -double !mod -double &in -double &modulus
+fun -double !rpn -list &rpn: Calculates a function in reverse polish notation. The list should have a form similar to `[3, 5, '+', 2, '-']`, i.e. only numbers and the `+`, `-`, `*`, `/` characters. **Requires the lists package to use**.
 
-Returns *n* such that *n* is congruent to the input modulo $modulus, where *n* is at least 0 and less than $modulus.
+fun -double !itod -int &input: Returns the input as a double.
 
-### fun -double !abs -double &in
-
-Returns the absolute value of *n*.
-
-### fun -double !random -int &seed
-
-Gets a random double in the domain [0,1), using a LCG. A seed is required.
-
-### fun -double !pi
-
-Returns pi to the maximum accuracy that doubles can store.
-
-### fun -double !itod -int &input
-
-Returns the input as a double.
-
-### fun -int !dtoi -double &input
-
-Returns the input as an integer.
\ No newline at end of file
+fun -int !dtoi -double &input: Returns the input as an integer.
\ No newline at end of file
diff --git a/programs/test.grnd b/programs/test.grnd
deleted file mode 100644
index 1e0eeec..0000000
--- a/programs/test.grnd
+++ /dev/null
@@ -1 +0,0 @@
-extern "file"