diff --git a/CoreWords.tl b/CoreWords.tl
index 2c17349..c24258b 100644
--- a/CoreWords.tl
+++ b/CoreWords.tl
@@ -1,19 +1,82 @@
-local Dict = require("Dictionary")
+local Dictionary = require("Dictionary")
 local Stack = require("Stack")
+local WordInfo = require("WordInfo")
+local State = require("State")
 
-function add(stack: Stack)
-  local a: any =stack:pop()
-  local b: any=stack:pop()
-  if a is number and b is number then
-    local c=a+b
-    stack:push(c)
+
+
+-- helper functions
+function areNumbers(a: any, b: any): boolean
+  return a is number and b is number
+end
+function getActiveDataStack(state: State): Stack
+  return state.activeDataStack
+end
+function popTwoOperands(state: State): any, any
+  local stack = getActiveDataStack(state)
+  local b: any = stack:pop()
+  local a: any = stack:pop()
+  return a, b
+end
+
+
+-- Mathematical operations
+function add(state: State)
+  local a, b = popTwoOperands(state)
+  if areNumbers(a,b) then
+    local c = (a as number) + (b as number)
+    getActiveDataStack(state):push(c)
   else
     error("invalid operands for add operation!")
   end
 end
-function dot(s: Stack)
-	print(s:pop())
+function sub(state: State)
+  local a, b = popTwoOperands(state)
+  if areNumbers(a, b) then
+    local c = (a as number) - (b as number)
+    getActiveDataStack(state):push(c)
+  else
+    error("invalid operands for sub operation!")
+  end
+end
+function mul(state: State)
+  local a, b = popTwoOperands(state)
+  if areNumbers(a, b) then
+    local c = (a as number) * (b as number)
+    getActiveDataStack(state):push(c)
+  else
+    error("invalid operands for mul operation!")
+  end
+end
+function div(state: State)
+  local a, b = popTwoOperands(state)
+  if areNumbers(a, b) then
+    local c = (a as number) / (b as number)
+    getActiveDataStack(state):push(c)
+  else
+    error("invalid operands for div operation!")
+  end
+end
+-- I/O operations
+function dot(state: State)
+	local out = state.activeDataStack:pop()
+  print(out)
+
 end
 
+local CoreWords = Dictionary:new()
+local AddInfo = WordInfo:new(add, false)
+local SubInfo = WordInfo:new(sub, false)
+local MulInfo = WordInfo:new(mul, false)
+local DivInfo = WordInfo:new(div, false)
+
+CoreWords:define("+", AddInfo)
+CoreWords:define("-", SubInfo)
+CoreWords:define("*", MulInfo)
+CoreWords:define("/", DivInfo)
+
+return CoreWords
+
+
 
 
diff --git a/WordInfo.tl b/WordInfo.tl
index a287395..10b550b 100644
--- a/WordInfo.tl
+++ b/WordInfo.tl
@@ -5,7 +5,7 @@ local type WordInfo = record
 	immediate: boolean
 end
 local wordi_mt = {__index = WordInfo}
-function WordInfo:new(funct: State, imm: boolean): WordInfo
+function WordInfo:new(funct: function(State), imm: boolean): WordInfo
   return setmetatable({func = funct, immediate = imm} as WordInfo, wordi_mt)
 end