How many {participant} are to/by {Kingdom of Castile} ?
Which is the number of participants in the Kingdom of Castile?
How many participants are there in the Kingdom of Castile?
SELECT ( COUNT ( ?c ) AS ?i ) { ?c property:participant resource:Kingdom_of_Castile }
SELECT (COUNT(?sub) AS ?subs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?sub .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P710> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q179293 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P710 wd:Q179293 }
11