diff --git a/.vscode/settings.json b/.vscode/settings.json
deleted file mode 100644
index edc55ce..0000000
--- a/.vscode/settings.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-    "snyk.advanced.autoSelectOrganization": true
-}
\ No newline at end of file
diff --git a/DEPLOYMENT_STEPS.md b/DEPLOYMENT_STEPS.md
new file mode 100644
index 0000000..bdc1330
--- /dev/null
+++ b/DEPLOYMENT_STEPS.md
@@ -0,0 +1,188 @@
+# CounterV2 Deployment Steps
+
+## Step 1: Create The Account Entry
+
+```bash
+sncast account create --name Yusrah --network sepolia
+```
+
+Save the generated account address and fund it with Sepolia tokens for fees.
+
+## Step 2: Deploy The Account
+
+```bash
+sncast account deploy --name Yusrah --network sepolia
+```
+
+## Step 3: List Accounts
+
+```bash
+sncast account list
+```
+
+Save the address for the `Yusrah` account.
+
+Yusrah's acc. address 0x72658e0505e77137829e255912c52f8ca0ae73de5dde8332686b1adac3034f0
+
+## Step 4: Go Into The Contract Package
+
+```bash
+cd ~/Desktop/cairo-begining/cairo-bootcamp-6/starknet_contracts
+```
+
+## Step 5: Build The Contract
+
+```bash
+scarb build
+```
+
+## Step 6: Declare CounterV2
+
+```bash
+sncast --account Yusrah \
+  declare \
+  --contract-name CounterV2 \
+  --network sepolia \
+  --wait
+```
+
+Save the `class_hash` from the output.
+
+class harsh  0x1e3a5b348490a07cea9f2788b81e46132c107724621e462494a5d20b67d458d
+
+## Step 7: Deploy CounterV2
+
+Replace:
+
+- `PASTE_CLASS_HASH_HERE`
+- `PASTE_YUSRAH_ADDRESS_HERE`
+
+```bash
+sncast --account Yusrah \
+  deploy \
+  --class-hash PASTE_CLASS_HASH_HERE \
+  --constructor-calldata PASTE_YUSRAH_ADDRESS_HERE \
+  --network sepolia \
+  --wait
+```
+
+Save the deployed `contract_address`.
+
+contract address 0x031e9847e60b0e7224c095cd45e260aa96daa0cec22960a8ab1cc51949997f36
+
+## Step 8: Verify The Owner
+
+Replace `PASTE_CONTRACT_ADDRESS_HERE`.
+
+```bash
+sncast call \
+  --contract-address PASTE_CONTRACT_ADDRESS_HERE \
+  --function get_owner \
+  --network sepolia
+```
+
+## Step 9: Verify The Initial Count
+
+```bash
+sncast call \
+  --contract-address PASTE_CONTRACT_ADDRESS_HERE \
+  --function get_count \
+  --network sepolia
+```
+
+Expected:
+
+```text
+0
+```
+
+## Step 10: Increase The Count By 10
+
+```bash
+sncast --account Yusrah \
+  invoke \
+  --contract-address PASTE_CONTRACT_ADDRESS_HERE \
+  --function increase_count \
+  --calldata 10 \
+  --network sepolia \
+  --wait
+```
+
+## Step 11: Verify The Count After Increasing
+
+```bash
+sncast call \
+  --contract-address PASTE_CONTRACT_ADDRESS_HERE \
+  --function get_count \
+  --network sepolia
+```
+
+Expected:
+
+```text
+10
+```
+
+## Step 12: Reduce The Count By 4
+
+```bash
+sncast --account Yusrah \
+  invoke \
+  --contract-address PASTE_CONTRACT_ADDRESS_HERE \
+  --function reduce_count \
+  --calldata 4 \
+  --network sepolia \
+  --wait
+```
+
+## Step 13: Verify The Count After Reducing
+
+```bash
+sncast call \
+  --contract-address PASTE_CONTRACT_ADDRESS_HERE \
+  --function get_count \
+  --network sepolia
+```
+
+Expected:
+
+```text
+6
+```
+
+## Step 14: Demo Subtraction Underflow Protection
+
+```bash
+sncast --account Yusrah \
+  invoke \
+  --contract-address PASTE_CONTRACT_ADDRESS_HERE \
+  --function reduce_count \
+  --calldata 200 \
+  --network sepolia \
+  --wait
+```
+
+Expected:
+
+An error because the subtraction underflows.
+
+## Step 15: Demo Non-Owner Rejection
+
+Replace `OTHER_ACCOUNT_NAME`.
+
+```bash
+sncast --account OTHER_ACCOUNT_NAME \
+  invoke \
+  --contract-address PASTE_CONTRACT_ADDRESS_HERE \
+  --function increase_count \
+  --calldata 1 \
+  --network sepolia \
+  --wait
+```
+
+Expected:
+
+An error because the caller is not the owner.
+
+
+e.g of non owner address 0x00A879C0fEf9C803041Ab7524859879B5d68684f413890401566367ae38a3a10
\ No newline at end of file
diff --git a/README.md b/README.md
index ece307b..f78bc3f 100644
--- a/README.md
+++ b/README.md
@@ -1,22 +1,54 @@
-# Cairo Bootcamp 6.0
+# Cairo Bootcamp 6 Assignment
 
-Welcome to **Cairo Bootcamp 6** — a hands-on, developer-focused program designed to help you learn Cairo from first principles and build real-world applications. This repository contains learning materials, examples, and exercises used throughout the bootcamp.
+This repo contains my Cairo assignment split into two versions:
 
----
+- `V1`: the earlier simple Starknet counter contract and standalone arithmetic practice
+- `V2`: the improved version where the Starknet contract imports reusable Cairo arithmetic logic and adds access control
 
-## About the Bootcamp
+## Assignment Summary
 
-This Cairo Bootcamp is designed to:
-- Introduce developers to Cairo 
-- Teach provable computation fundamentals**
-- Explore Starknet and smart contract development
-- Encourage hands-on building and experimentation
+The assignment required the following:
 
+- add a subtraction check so negative results throw an error
+- write multiplication and division functions and handle their error cases
+- add `only_owner` to state-changing functions
+- make `increase_count` read the current storage value and add the incoming amount instead of overwriting storage
+- import Cairo arithmetic logic into the Starknet contract for `increase_count` and `reduce_count`
 
----
+## Project Structure
 
-## 📁 Repository Structure
-.
-├── cairo_programs/ # Pure Cairo programs (stateless logic)
-├── starknet_contracts/ # Smart contracts (stateful logic)
-└── README.md
\ No newline at end of file
+- `cairo_program/`: plain Cairo logic
+- `starknet_contracts/`: Starknet contracts
+
+## V1 Files
+
+- Cairo arithmetic practice: [cairo_program/src/integer.cairo](cairo_program/src/integer.cairo)
+- Simple Starknet contract: [starknet_contracts/src/counter_v1.cairo](starknet_contracts/src/counter_v1.cairo)
+
+## V2 Files
+
+- Reusable arithmetic logic: [cairo_program/src/arithmetic_v2.cairo](cairo_program/src/arithmetic_v2.cairo)
+- Cairo library export: [cairo_program/src/lib.cairo](cairo_program/src/lib.cairo)
+- Improved Starknet contract: [starknet_contracts/src/counter_v2.cairo](starknet_contracts/src/counter_v2.cairo)
+- Starknet package entry: [starknet_contracts/src/lib.cairo](starknet_contracts/src/lib.cairo)
+
+## What Was Implemented In V2
+
+- `sub_num` checks for underflow and throws an error
+- `mul_num` checks for overflow
+- `div_num` checks for division by zero
+- `increase_count` uses imported addition logic
+- `reduce_count` uses imported subtraction logic
+- `increase_count` reads the current count from storage before updating it
+- `only_owner` restricts state-changing functions
+
+## Build Status
+
+Both packages compile successfully:
+
+- `cairo_program`
+- `starknet_contracts`
+
+## Next Step
+
+The next step after this PR is deployment of `CounterV2`, where the owner address will be passed into the constructor.
diff --git a/cairo_program/.vscode/settings.json b/cairo_program/.vscode/settings.json
deleted file mode 100644
index edc55ce..0000000
--- a/cairo_program/.vscode/settings.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-    "snyk.advanced.autoSelectOrganization": true
-}
\ No newline at end of file
diff --git a/cairo_program/README.md b/cairo_program/README.md
index 8cf3016..59bd28f 100644
--- a/cairo_program/README.md
+++ b/cairo_program/README.md
@@ -1,17 +1,26 @@
 # Cairo Program
 
-Welcome to **Cairo Bootcamp 6** — a hands-on, developer-focused program designed to help you learn Cairo from first principles and build real-world applications. This repository contains learning materials, examples, and exercises used throughout the bootcamp.
+This package contains the plain Cairo logic used in the assignment.
 
----
+## Files
 
+- `src/integer.cairo`: V1 arithmetic practice
+- `src/arithmetic_v2.cairo`: V2 reusable arithmetic functions
+- `src/lib.cairo`: exports the V2 arithmetic module for reuse by the Starknet contract package
 
+## V2 Arithmetic
 
----
+The reusable V2 module includes:
 
-## 📁 Repository Structure
-.
-├── src/ 
-├── starknet_contracts/ # Smart contracts (stateful logic)
-├── exercises/ # Practice tasks and assignments
-├── notes/ # Learning notes (felt, syntax, etc.)
-└── README.md
\ No newline at end of file
+- `add_num`
+- `sub_num`
+- `mul_num`
+- `div_num`
+
+Error handling included:
+
+- subtraction underflow protection
+- multiplication overflow protection
+- division-by-zero protection
+
+This package is imported into the V2 Starknet contract so the contract can reuse the arithmetic logic instead of doing the arithmetic inline.
diff --git a/cairo_program/Scarb.toml b/cairo_program/Scarb.toml
index b6c900a..a1e4f58 100644
--- a/cairo_program/Scarb.toml
+++ b/cairo_program/Scarb.toml
@@ -5,6 +5,8 @@ edition = "2025_12"
 
 # See more keys and their definitions at https://docs.swmansion.com/scarb/docs/reference/manifest.html
 
+[lib]
+
 [executable]
 
 [cairo]
@@ -13,4 +15,3 @@ enable-gas = false
 [dependencies]
 cairo_execute = "2.18.0"
 
-
diff --git a/cairo_program/src/arithmetic_v2.cairo b/cairo_program/src/arithmetic_v2.cairo
new file mode 100644
index 0000000..ee78037
--- /dev/null
+++ b/cairo_program/src/arithmetic_v2.cairo
@@ -0,0 +1,29 @@
+pub fn add_num(x: u32, y: u32) -> u32 {
+    x + y
+}
+
+pub fn sub_num(x: u32, y: u32) -> u32 {
+    if y > x {
+        panic!("Sub underflow");
+    }
+    x - y
+}
+
+pub fn mul_num(x: u32, y: u32) -> u32 {
+    let wide_x: u64 = x.into();
+    let wide_y: u64 = y.into();
+    let result = wide_x * wide_y;
+
+    if result > 4294967295_u64 {
+        panic!("Mul overflow");
+    }
+
+    result.try_into().unwrap()
+}
+
+pub fn div_num(x: u32, y: u32) -> u32 {
+    if y == 0 {
+        panic!("Cannot divide 0");
+    }
+    x / y
+}
diff --git a/cairo_program/src/bool.cairo b/cairo_program/src/bool.cairo
index cafad1e..96267db 100644
--- a/cairo_program/src/bool.cairo
+++ b/cairo_program/src/bool.cairo
@@ -11,7 +11,7 @@ fn main() {
 fn is_adult(x: u8) -> bool {
     // let mut outcome: bool = false;
     if x <= 18 {
-        // outcome = false;
+   =;/ outcome = false;
         return false;
     }
     // outcome = true;
diff --git a/cairo_program/src/lib.cairo b/cairo_program/src/lib.cairo
index acc7644..95ef023 100644
--- a/cairo_program/src/lib.cairo
+++ b/cairo_program/src/lib.cairo
@@ -2,4 +2,5 @@
 // mod short_string;
 // mod integer;
 // mod bool;
-mod bytearray;
\ No newline at end of file
+mod bytearray;
+pub mod arithmetic_v2;
diff --git a/starknet_contracts/Scarb.lock b/starknet_contracts/Scarb.lock
index 6c8c64a..2733aea 100644
--- a/starknet_contracts/Scarb.lock
+++ b/starknet_contracts/Scarb.lock
@@ -1,6 +1,10 @@
 # Code generated by scarb DO NOT EDIT.
 version = 1
 
+[[package]]
+name = "cairo_6"
+version = "0.1.0"
+
 [[package]]
 name = "snforge_scarb_plugin"
 version = "0.56.0"
@@ -20,5 +24,6 @@ dependencies = [
 name = "starknet_contracts"
 version = "0.1.0"
 dependencies = [
+ "cairo_6",
  "snforge_std",
 ]
diff --git a/starknet_contracts/Scarb.toml b/starknet_contracts/Scarb.toml
index 29cf20f..124c7d3 100644
--- a/starknet_contracts/Scarb.toml
+++ b/starknet_contracts/Scarb.toml
@@ -7,6 +7,7 @@ edition = "2024_07"
 
 [dependencies]
 starknet = "2.18.0"
+cairo_6 = { path = "../cairo_program" }
 
 [dev-dependencies]
 snforge_std = "0.56.0"
diff --git a/starknet_contracts/src/counter_v2.cairo b/starknet_contracts/src/counter_v2.cairo
new file mode 100644
index 0000000..b0fc1de
--- /dev/null
+++ b/starknet_contracts/src/counter_v2.cairo
@@ -0,0 +1,61 @@
+#[starknet::interface]
+pub trait ICounterV2<T> {
+    fn increase_count(ref self: T, amount: u32);
+    fn reduce_count(ref self: T, amount: u32);
+    fn get_count(self: @T) -> u32;
+    fn get_owner(self: @T) -> starknet::ContractAddress;
+}
+
+#[starknet::contract]
+pub mod CounterV2 {
+    use cairo_6::arithmetic_v2::{add_num, sub_num};
+    use starknet::get_caller_address;
+    use starknet::storage::{StoragePointerReadAccess, StoragePointerWriteAccess};
+    use starknet::ContractAddress;
+
+    #[storage]
+    struct Storage {
+        owner: ContractAddress,
+        count: u32,
+    }
+
+    #[constructor]
+    fn constructor(ref self: ContractState, owner: ContractAddress) {
+        self.owner.write(owner);
+    }
+
+    fn assert_only_owner(self: @ContractState) {
+        let caller = get_caller_address();
+        let owner = self.owner.read();
+        assert(caller == owner, 'Only owner');
+    }
+
+    #[abi(embed_v0)]
+    impl CounterV2Impl of super::ICounterV2<ContractState> {
+        fn increase_count(ref self: ContractState, amount: u32) {
+            assert_only_owner(@self);
+            assert(amount != 0, 'Amount cannot be 0');
+
+            let current_count = self.count.read();
+            let updated_count = add_num(current_count, amount);
+            self.count.write(updated_count);
+        }
+
+        fn reduce_count(ref self: ContractState, amount: u32) {
+            assert_only_owner(@self);
+            assert(amount != 0, 'Amount cannot be 0');
+
+            let current_count = self.count.read();
+            let updated_count = sub_num(current_count, amount);
+            self.count.write(updated_count);
+        }
+
+        fn get_count(self: @ContractState) -> u32 {
+            self.count.read()
+        }
+
+        fn get_owner(self: @ContractState) -> ContractAddress {
+            self.owner.read()
+        }
+    }
+}
diff --git a/starknet_contracts/src/lib.cairo b/starknet_contracts/src/lib.cairo
index f1b82bb..ca4972a 100644
--- a/starknet_contracts/src/lib.cairo
+++ b/starknet_contracts/src/lib.cairo
@@ -1,16 +1,11 @@
-/// Interface representing `HelloContract`.
-/// This interface allows modification and retrieval of the contract's storage count.
 #[starknet::interface]
 pub trait ICounter<T> {
-    /// Increase count.
     fn increase_count(ref self: T, amount: u32);
-    /// Retrieve count.
     fn get_count(self: @T) -> u32;
 }
 
-/// Simple contract for managing count.
 #[starknet::contract]
-mod Counter {
+pub mod Counter {
     use starknet::storage::{StoragePointerReadAccess, StoragePointerWriteAccess};
 
     #[storage]
@@ -30,3 +25,5 @@ mod Counter {
         }
     }
 }
+
+mod counter_v2;