How many {file format} are to/by {Portable Document Format} ?
How many different extensions are support by the Portable Document Format
How many file formats are done on Portable Document Format?
SELECT ( COUNT ( ?i ) AS ?a ) { ?i property:file_format resource:Portable_Document_Format }
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/P2701> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> http://wikidata.dbpedia.org/resource/Q42332 .
} 

SELECT (COUNT(?sub) AS ?value ) { ?sub wdt:P2701 wd:Q42332 }
21