(ただし1と2を合せて12のような使い方は出来ません。)
36個の解法が見つかりました。
((4+5)+(9-8))=10
((4+5)-(8-9))=10
((4+9)+(5-8))=10
((4+9)-(8-5))=10
((4-8)+(5+9))=10
((5+(4+9))-8)=10
((5+9)+(4-8))=10
((5+9)-(8-4))=10
((5-8)+(4+9))=10
((9+(4+5))-8)=10
((9-8)+(4+5))=10
(4+((5+9)-8))=10
(4+(5+(9-8)))=10
(4+(5-(8-9)))=10
(4+(9+(5-8)))=10
(4+(9-(8-5)))=10
(4-((8-5)-9))=10
(4-((8-9)-5))=10
(4-(8-(5+9)))=10
(5+((4+9)-8))=10
(5+(4+(9-8)))=10
(5+(4-(8-9)))=10
(5+(9+(4-8)))=10
(5+(9-(8-4)))=10
(5-((8-4)-9))=10
(5-((8-9)-4))=10
(5-(8-(4+9)))=10
(9+((4+5)-8))=10
(9+(4+(5-8)))=10
(9+(4-(8-5)))=10
(9+(5+(4-8)))=10
(9+(5-(8-4)))=10
(9-((8-4)-5))=10
(9-((8-5)-4))=10
(9-(8-(4+5)))=10