How many {interaction} are for {antiproton} ?
What is the number of interactions of an antiproton?
How many interactions does an antiproton have ?
SELECT ( COUNT ( ?o ) AS ?r ) { resource:antiproton property:interaction ?o }
SELECT (COUNT(?obj) AS ?objs ) {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q107575> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P517> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
} 

SELECT (COUNT(?obj) AS ?value ) { wd:Q107575 wdt:P517 ?obj }
4