Paste what you wrote and the source you wrote it from. Every number, quotation and proper name in your draft gets marked: found in the source, found only in a different form, or not found at all. A number that is not in your source is either your arithmetic or your invention, and you should know which before a reader asks.
Nothing you paste leaves this page. The check is word-for-word, so it cannot tell you a claim is true. It tells you which parts of your draft your source does not carry.
One of the things the farm made at docatcdi.com. Free; it runs in your browser and sends nothing anywhere.