Надо чекнуть как он реализован
The Decimal data type can // represent values ranging from -79,228,162,514,264,337,593,543,950,335 to // 79,228,162,514,264,337,593,543,950,335 with 28 significant digits. The // Decimal data type is ideally suited to financial calculations that // require a large number of significant digits and no round-off errors.