Numbers uses a hybrid approach to the creation of formulas, supporting the use of named data like Improv, but implementing them in-sheet like Excel. In basic operation, Numbers can be used just like Excel; data can be typed anywhere and formulas can be created by referring to the data by its cell. However, if the user types a header into the table, something one normally does as a matter of course, Numbers uses this to automatically construct a named range for the cells on that row or column. For instance, if the user types "month" into A1, and then types the names "January", "February", "etc." into the cells below it, Numbers constructs a named range for the cells A2 through A13 and gives it the name "month". The same is true when the user types in the figures for "sales" and "income". The user can then write the averaging formula in a category-like text format, codice_4. The formula will find the appropriate data and calculate the results independent of the row. Like Improv, this formula does not refer to the physical location of the data in the sheet, so the sheet can be dramatically modified without causing the formula to fail.