Summary  
This chapter explains how to define and organize DAX measures—using functions like SUM for basic aggregation and CALCULATE to modify evaluation context with filters—and how to group them in a dedicated calculation table.  

General domain of usage  
Data analysis and reporting

Begin your first hands-on experience with **DAX (Data Analysis Expressions)** by learning how to create and organize measures within a **calculation table**. This approach helps structure and manage calculations effectively, streamlining data analysis and reporting in both Power BI and Excel Power Pivot.

Alongside basic aggregation functions, you will explore the powerful `CALCULATE` function in DAX, which modifies the context of a calculation by applying filters.

To calculate the **total number of riders** from two columns, use the `SUM` function and the `+` operator:

```DAX
Total Riders =
    SUM(Pivot_Table[casual])
    + SUM(Pivot_Table[registered])
```

To compute **riders during the winter season**, use `CALCULATE` with your total riders measure and a filter condition:

```DAX
Winter Riders =
    CALCULATE(
        [Total Riders],
        Pivot_Table[Season Names] = "Winter"
    )
```

DAX (Data Analysis Expressions) Basics