How many {partner} are to/by {Iron Man} ?
How many partner with Ironman?
How many partners does Iron man have?
SELECT ( COUNT ( ?i ) AS ?p ) { ?i property:unmarried_partner resource:Iron_Man }
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/P451> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q180704 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P451 wd:Q180704 }
11