---
title: 'Basic Functions Exercise'
description: Exercise - Create and deploy a contract with simple math functions.
hide_table_of_contents: false
---

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!

:::info

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.**

:::

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` do not overflow, it should return the `sum` and an `error` of `false`
- If `_a` + `_b` overflow, 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`