How many {operating system} are to/by {MS-DOS} ?
Which is the number of operating systems run on MS-DOS?
How many operating systems run on MS-DOS?
SELECT ( COUNT ( ?v ) AS ?u ) { ?v property:operating_system resource:MS-DOS }
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/P306> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q47604 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P306 wd:Q47604 }
113