> ## Documentation Index
> Fetch the complete documentation index at: https://base-a060aa97-eb-mini-app-ia-overhaul.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Basic Functions Exercise

> Exercise - Create and deploy a contract with simple math functions.

Each module in this course will contain exercises in which you are given a specification for a contract **without** being given specific instructions on how to build the contract. You must use what you've learned to figure out the best solution on your own!

<Note>
  Once you've learned how to deploy your contracts to a test network, you'll be given the opportunity to submit your contract address for review by an onchain unit test. If it passes, you'll receive an NFT pin recognizing your accomplishment.

  **You'll deploy and submit this contract in the next module.**
</Note>

The following exercise asks you to create a contract that adheres to the following stated specifications.

## Contract

Create a contract called `BasicMath`. It should not inherit from any other contracts and does not need a constructor. It should have the following two functions:

### Adder

A function called `adder`. It must:

* Accept two `uint` arguments, called `_a` and `_b`
* Return a `uint` `sum` and a `bool` `error`
* If `_a` + `_b` does not overflow, it should return the `sum` and an `error` of `false`
* If `_a` + `_b` overflows, it should return `0` as the `sum`, and an `error` of `true`

### Subtractor

A function called `subtractor`. It must:

* Accept two `uint` arguments, called `_a` and `_b`
* Return a `uint` `difference` and a `bool` `error`
* If `_a` - `_b` does not underflow, it should return the `difference` and an `error` of `false`
* If `_a` - `_b` underflows, it should return `0` as the `difference`, and an `error` of `true`