How many {ammunition} are for {Glock} ?
How much ammunition does a Glock require?
How much ammunition is for a Glock?
SELECT ( COUNT ( ?z ) AS ?a ) { resource:Glock property:ammunition ?z }
SELECT (COUNT(?obj) AS ?objs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q739882> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P739> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
} 

SELECT (COUNT(?obj) AS ?value ) { wd:Q739882 wdt:P739 ?obj }
8