Challenge 1: Region-by-Product Sales Grid — Solution Walkthrough

Field placement:
  Rows:    Region
  Columns: Product
  Values:  Sales (default aggregation: Sum)

Resulting grid:

One row appears per unique Region, one column appears per unique
Product, and each cell where a specific Region-row meets a specific
Product-column shows the total Sales for exactly that Region+Product
combination. A grand total column appears on the right (total Sales
per Region across all products), and a grand total row appears along
the bottom (total Sales per Product across all regions), with the
single bottom-right cell showing the overall grand total of every
row in the source data.

Explanation:

Rows and Columns together create a genuine cross-tabulation — each
individual cell inside the grid isn't just "this region's total" or
"this product's total," it's specifically the intersection of both,
answering "how much of Product X did Region Y sell." This is exactly
the kind of two-dimensional breakdown that would require a separate
SUMIFS formula for every single Region/Product pair to replicate by
hand, one of the clearest illustrations of why this chapter frames
PivotTables as doing Chapter 4's aggregation work automatically,
grouped however the Rows and Columns happen to be arranged.

Notes:
- Swapping Region and Product between the Rows and Columns boxes
  produces the same numbers, just transposed (Products as rows,
  Regions as columns) — the data doesn't change, only which
  dimension is read top-to-bottom vs. left-to-right.