1. A computer method automatically mathematically decomposing a table-structured electronic document comprising multiple tables having predefined mathematical relationships, the method comprising the following steps: utilizing textual clues and the predefined mathematical relationships between the multiple tables to partition the document into multiple sub-tables; identifying a value in each of the sub-tables as a grand total by utilizing at least one of positional and textual information; assigning all line items within each of the sub-tables, except for the grand total for each of the sub-tables, as children of each of the sub-tables, as children of the sub-table; pre-identifying subtotals within each table by utilizing available textual clues; pre-identifying a value sign for each value in each table by utilizing available textual clues; automatically identifying and validating mathematical relationships between children in each of the sub-tables by summing together all line items values within each of the sub-tables, except the grand total value for each of the sub-tables, to create a validation sum, and then subtracting a sum of successively larger sets of line item values from the validation sum until the result thereof equals the grand total value for each of the sub-tables, wherein when the result thereof equals the grand total value for each of the sub-tables, the values in the set of line item values are identified as subtotals of each of the sub-tables.