# Common Functions

The Helios protocol provides several **common utility functions** for retrieving reserve configuration data. Commonly used ones include `getReserveFactor` and `getDecimals`. These functions are used to read configuration values (stored in a reserve’s configuration map).

#### `getReserveFactor`

```solidity
function getReserveFactor(DataTypes.ReserveConfigurationMap memory config) internal pure returns (uint256)
```

Returns the **reserve factor** of a given reserve, as a `uint256`. The reserve factor represents the percentage of borrowing interest that is allocated to the Helios protocol (e.g. to a treasury or insurance fund), with the remainder of the interest going to suppliers of liquidity (holders of hTokens for that reserve).

* The reserve factor is stored as part of the reserve’s configuration bitmap (`ReserveConfigurationMap`). `getReserveFactor` isolates the reserve factor bits from this bitmap and returns their value.
* The value is expressed in basis points (bps). For example, a reserve factor of `1000` would correspond to 10% (since 1000 bps = 10%). If the reserve factor is 10%, then 10% of the interest accrued by borrowers on that asset goes to Helios, and 90% goes to the suppliers of that asset.

#### `getDecimals`

```solidity
function getDecimals(DataTypes.ReserveConfigurationMap memory config) internal pure returns (uint256)
```

Returns the number of **decimals** used by the reserve’s underlying asset, as a `uint256`. This is typically equal to the ERC20 `decimals()` of the underlying token.

* The decimals value is stored in the reserve’s configuration bitmap. `getDecimals` extracts this value from the stored data.
* Helios uses the asset’s decimals to scale values for accurate calculations. All internal accounting uses a common base (e.g. 18 decimal fixed-point math via “ray” units), so knowing the asset’s native decimals is important for conversions when minting hTokens, accruing interest, etc.


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