> For the complete documentation index, see [llms.txt](https://docs.ax11.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ax11.org/price-data-structure/key-properties-of-the-price-data-structure.md).

# Key Properties of the Price Data Structure

#### 1. **Data Type**

* **UINT 256**:
  * Price values are stored as a **256-bit unsigned integer**, ensuring sufficient precision for complex computations.
  * This representation supports extremely large values while maintaining compatibility with Ethereum’s architecture.
* **Not Scaled Integers**:
  * Prices are expressed as raw integers, avoiding scaling complexities common in floating-point arithmetic.

#### 2. **ERC-20 Scaling Standard**

* **Scale Integer (10¹⁸)**:
  * Prices follow the same scale as ERC-20 tokens (e.g., 1 ETH = 10¹⁸ units). This ensures consistency across decentralized applications and simplifies integration with other DeFi protocols.

#### 3. **Binary Representation**

* **Q128.128 Format**:
  * Prices are stored using a **binary fixed-point representation**:
    * The **first 128 bits** represent the **integer portion** of the price.
    * The **last 128 bits** represent the **fractional (decimal) portion** of the price.
  * This format ensures precision for both whole and fractional values, avoiding rounding errors in calculations.

#### 4. **Optimized Storage**

* **Single-Sided Price Storage**:
  * The protocol only keeps one price (e.g., **X**) instead of storing both sides of a pair (e.g., **X and Y**).
  * Using a single price reduces storage requirements and computational overhead while enabling the calculation of the second value when needed.