You can choose any resolution for scanning, however it is best to take into consideration the size of the file that will result and what the business archiving space/requirements are.
For most documents, a 300dpi is optimum as it is detailed enough for important information (such as signatures, OCR text, bar codes, etc). When scanning color documents, file sizes will be much larger. In these instances, 200dpi is often adequate and image quality will be sufficient.
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