About column references in a formula
A reference identifies a cell in the current row in a datasheet and tells a list where to look for the values or data you want to use in a formula. For example, [Cost] references the value in the Cost column in the current row. If the Cost column has the value of 100 for the current row, then =[Cost]*3 will return 300.
With references, you can use data contained in different columns of a list in one or more formulas. Columns of the following data types can be referenced in a formula: Single line of text, number, currency, date and time, choice, yes/no, and calculated.
You use the display name of the column to reference it in a formula. If the name includes a space or a special character, you must enclose the name in square brackets ([ ]). References are not case-sensitive. For example, you could reference the Unit Price column in a formula as [Unit Price] or [unit price].
Note You cannot reference a value in a row other than the current row. You also cannot include column references in a formula that is specified as the default value of a column.