You simply need to collect as many cards as you can to make it as close to 21 without going over, in rare cases.
https://debate.socialism.nl/forum/showthread.php?tid=197475
http://ewmen.com/viewtopic.php?p=1182440#p1182440
http://qrfonline.qrfmag.com/qrfswap/viewtopic.php?t=122383
https://www.ww2.site/forum/viewtopic.php?t=85874
http://www.prepody.ru/topic77211.html
http://forum3.bandingklub.cz/viewtopic.php...6&t=1295715
http://www.prepody.ru/topic49800.html
http://forum3.bandingklub.cz/viewtopic.php...0&t=1358418
https://s21.me/ysm21/viewtopic.php?pid=271849
http://horsecity.ru/phpBB3/viewtopic.php?f=33&t=256311
http://www.prepody.ru/topic38894.html
https://ufr-2020.front5.picapo.net/forums/v....php?pid=363633
http://foro.goatenerife.es/viewtopic.php?f=29&t=31303
http://forum.spolokmedikovke.sk/viewtopic....=3&t=811125
http://forum.bandingklub.cz/viewtopic.php?f=39&t=1241943
http://users.atw.hu/tunedthings/viewtopic....p=386688#386688
http://biopharmamash.com/viewtopic.php?t=1246696
http://forum.spolokmedikovke.sk/viewtopic....12&t=938556
http://ewmen.com/viewtopic.php?t=601352
https://www.ww2.site/forum/viewtopic.php?t=101110