How many {member of} are to/by {International Hydrographic Organization} ?
Give me the number of members the IHO has?
How many members are there of the International Hydrographic Organization?
SELECT ( COUNT ( ?f ) AS ?v ) { ?f property:member_of resource:International_Hydrographic_Organization }
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/P463> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q233611 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P463 wd:Q233611 }
87