When writing a formula, you may refer to arrays (data range) rather than cells, this return a data range (array) with the same size which top right cell of the range is the active or source cell, and each cell is calculated based on the formula applied on the referred range (array)

We have information about accounts in a store.

Tax = GL Amount *0.05 which is calculated using Dynamic arrays. Net Amount which is amount after tax is also calculated using dynamic array.

We also may have different tax rates. The tax based on the amount and tax rate can be calculated using dynamic arrays. The tax calcuated without dynamic arrays is included (the one below) for comparison.