How much is my 2013 20 worth with the serial?

To determine the value of your 2013 20 (presumably a specific model of a product, like a guitar or a watch), you'll need to provide more details, including the brand and any specific features or conditions of the item. The serial number can help authenticate the item and might influence its value based on rarity or demand. For an accurate valuation, consider checking online marketplaces, collector forums, or consulting an appraiser.