duckduckgo/zeroclickinfo-goodies — pull request #66 by JetFault (2012-04-13 05:37:08+00:00)
Title: Goodie to show days between two dates

If only one date is listed, then will tell days between current date. 'inclusive' keyword to include last day in count.
https://duckduckhack.uservoice.com/forums/5168-plugins/suggestions/2701570-days-in-between-calculate-date-differences