(ただし1と2を合せて12のような使い方は出来ません。)
34個の解法が見つかりました。
((2+(5+5))-2)=10
((2+5)+(5-2))=10
((2+5)-(2-5))=10
((2-2)+(5+5))=10
((2÷2)×(5+5))=10
((5+(2+5))-2)=10
((5+5)×(2÷2))=10
((5+5)+(2-2))=10
((5+5)-(2-2))=10
((5+5)÷(2÷2))=10
((5-2)+(2+5))=10
(2×((2×5)-5))=10
(2×((5+5)÷2))=10
(2+((5+5)-2))=10
(2+(5+(5-2)))=10
(2+(5-(2-5)))=10
(2-((2-5)-5))=10
(2-(2-(5+5)))=10
(2÷(2÷(5+5)))=10
(5+((2×5)÷2))=10
(5+((2+5)-2))=10
(5+(2×(5÷2)))=10
(5+(2+(5-2)))=10
(5+(2-(2-5)))=10
(5+(2÷(2÷5)))=10
(5+(5×(2÷2)))=10
(5+(5+(2-2)))=10
(5+(5-(2-2)))=10
(5+(5÷(2÷2)))=10
(5-((2-2)-5))=10
(5-((2-5)-2))=10
(5-(2-(2+5)))=10
(5÷((5÷2)-2))=10