> For the complete documentation index, see [llms.txt](https://docs.alkemi.network/earn-contracts/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.alkemi.network/earn-contracts/docs/carefulmath.md).

# Careful Math (CarefulMath.sol)

View Source: [contracts/CarefulMath.sol](https://github.com/AlkemiNetwork/alkemi-earn-contracts/tree/ae6d5c01ff8b3810c4005457ac7ce441ab1c7ec5/contracts/CarefulMath.sol)

**↗ Extends:** [**ErrorReporter**](/earn-contracts/docs/errorreporter.md) **↘ Derived Contracts:** [**Exponential**](/earn-contracts/docs/exponential.md)

Derived from OpenZeppelin's SafeMath library <https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/math/SafeMath.sol>

### Functions

* mul(uint256 a, uint256 b)
* div(uint256 a, uint256 b)
* sub(uint256 a, uint256 b)
* add(uint256 a, uint256 b)
* addThenSub(uint256 a, uint256 b, uint256 c)

#### mul

Multiplies two numbers, returns an error on overflow.

```javascript
function mul(uint256 a, uint256 b) internal pure
returns(enum ErrorReporter.Error, uint256)
```

**Arguments**

| Name | Type    | Description |
| ---- | ------- | ----------- |
| a    | uint256 |             |
| b    | uint256 |             |

#### div

Integer division of two numbers, truncating the quotient.

```javascript
function div(uint256 a, uint256 b) internal pure
returns(enum ErrorReporter.Error, uint256)
```

**Arguments**

| Name | Type    | Description |
| ---- | ------- | ----------- |
| a    | uint256 |             |
| b    | uint256 |             |

#### sub

Subtracts two numbers, returns an error on overflow (i.e. if subtrahend is greater than minuend).

```javascript
function sub(uint256 a, uint256 b) internal pure
returns(enum ErrorReporter.Error, uint256)
```

**Arguments**

| Name | Type    | Description |
| ---- | ------- | ----------- |
| a    | uint256 |             |
| b    | uint256 |             |

#### add

Adds two numbers, returns an error on overflow.

```javascript
function add(uint256 a, uint256 b) internal pure
returns(enum ErrorReporter.Error, uint256)
```

**Arguments**

| Name | Type    | Description |
| ---- | ------- | ----------- |
| a    | uint256 |             |
| b    | uint256 |             |

#### addThenSub

add a and b and then subtract c

```javascript
function addThenSub(uint256 a, uint256 b, uint256 c) internal pure
returns(enum ErrorReporter.Error, uint256)
```

**Arguments**

| Name | Type    | Description |
| ---- | ------- | ----------- |
| a    | uint256 |             |
| b    | uint256 |             |
| c    | uint256 |             |