How many {designed by} are to/by {Niklaus Wirth} ?
What is the number that was designed by Nikclaus Wirth?
How many are designed by Niklaus Wirth?
SELECT ( COUNT ( ?v ) AS ?u ) { ?v property:designed_by resource:Niklaus_Wirth }
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/P287> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q92604 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P287 wd:Q92604 }
6