diff --git a/src/chunk.h b/src/chunk.h
index 894ebe3..f02ad14 100644
--- a/src/chunk.h
+++ b/src/chunk.h
@@ -8,6 +8,11 @@
 typedef enum {
   OP_NOOP,
   OP_CONSTANT,
+  OP_ADD,
+  OP_SUBTRACT,
+  OP_MULTIPLY,
+  OP_DIVIDE,
+  OP_NEGATE,
   OP_RETURN, 
 } OpCode;
 
diff --git a/src/debug.c b/src/debug.c
index 7b59fb0..0f9a408 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -38,8 +38,18 @@ int disassembleInstruction(Chunk* chunk, int offset) {
   switch (instruction) {
     case OP_NOOP:
       return simpleInstruction("OP_NOOP", offset);
+    case OP_NEGATE:
+      return simpleInstruction("OP_NEGATE", offset);     
     case OP_CONSTANT:
       return constantInstruction("OP_CONSTANT", chunk, offset);
+    case OP_ADD:
+      return simpleInstruction("OP_ADD", offset);
+    case OP_SUBTRACT:
+      return simpleInstruction("OP_SUBTRACT", offset);
+    case OP_MULTIPLY:
+      return simpleInstruction("OP_MULTIPLY", offset);
+    case OP_DIVIDE:
+      return simpleInstruction("OP_DIVIDE", offset);
     case OP_RETURN:
       return simpleInstruction("OP_RETURN", offset);
     default:
diff --git a/src/main.c b/src/main.c
index 5a93d46..ec32b79 100644
--- a/src/main.c
+++ b/src/main.c
@@ -10,8 +10,21 @@ int main(int argc, const char** argv) {
   newChunk(&chunk);
 
   int constant = addConstant(&chunk, 1.2);
-  writeChunk(&chunk, OP_CONSTANT, 1);
-  writeChunk(&chunk, constant, 1);
+  writeChunk(&chunk, OP_CONSTANT, 123);
+  writeChunk(&chunk, constant, 123);
+
+  constant = addConstant(&chunk, 3.4);
+  writeChunk(&chunk, OP_CONSTANT, 123);
+  writeChunk(&chunk, constant, 123);
+
+  writeChunk(&chunk, OP_ADD, 123);
+
+  constant = addConstant(&chunk, 5.6);
+  writeChunk(&chunk, OP_CONSTANT, 123);
+  writeChunk(&chunk, constant, 123);
+
+  writeChunk(&chunk, OP_DIVIDE, 123);
+  writeChunk(&chunk, OP_NEGATE, 123);
 
   writeChunk(&chunk, OP_RETURN, 1);
 
diff --git a/src/vm.c b/src/vm.c
index 235e8c6..715446c 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -31,6 +31,12 @@ Value pop() {
 static InterpretResult run() {
 #define READ_BYTE() (*vm.ip++)
 #define READ_CONSTANT() (vm.chunk->constants.values[READ_BYTE()])
+#define BINARY_OP(op) \
+    do { \
+      double b = pop(); \
+      double a = pop(); \
+      push(a op b); \
+    } while (false)
 
   for (;;) {
 #ifdef DEBUG_TRACE_EXECUTION
@@ -52,6 +58,11 @@ static InterpretResult run() {
 	push(constant);
         break;
       }
+      case OP_ADD:      BINARY_OP(+); break;
+      case OP_SUBTRACT: BINARY_OP(-); break;
+      case OP_MULTIPLY: BINARY_OP(*); break;
+      case OP_DIVIDE:   BINARY_OP(/); break;
+      case OP_NEGATE:   push(-pop()); break;
       case OP_RETURN: {
 	printValue(pop());
 	printf("\n");
@@ -62,6 +73,7 @@ static InterpretResult run() {
 
 #undef READ_BYTE
 #undef READ_CONSTANT
+#undef BINARY_OP
 }
 
 InterpretResult interpret(Chunk* chunk) {