（ただし１と２を合せて１２のような使い方は出来ません。）
123個の解法が見つかりました。
(((4×5)÷2)÷1)=10
((1×(4×5))÷2)=10
((1×4)×(5÷2))=10
((1×4)÷(2÷5))=10
((1×5)×(4-2))=10
((1×5)×(4÷2))=10
((1×5)÷(2÷4))=10
((1÷2)×(4×5))=10
((2+(4+5))-1)=10
((2+4)+(5-1))=10
((2+4)-(1-5))=10
((2+5)+(4-1))=10
((2+5)-(1-4))=10
((2-1)+(4+5))=10
((4×(1×5))÷2)=10
((4×(5÷1))÷2)=10
((4×(5÷2))÷1)=10
((4×5)×(1÷2))=10
((4×5)÷(1×2))=10
((4×5)÷(2÷1))=10
((4+(2+5))-1)=10
((4+5)+(2-1))=10
((4+5)-(1-2))=10
((4-1)+(2+5))=10
((4-2)×(1×5))=10
((4-2)×(5÷1))=10
((4-2)÷(1÷5))=10
((4÷(1÷5))÷2)=10
((4÷(2÷5))÷1)=10
((4÷1)×(5÷2))=10
((4÷1)÷(2÷5))=10
((4÷2)×(1×5))=10
((4÷2)×(5÷1))=10
((4÷2)÷(1÷5))=10
((5×(1×4))÷2)=10
((5×(4-2))÷1)=10
((5×(4÷1))÷2)=10
((5×(4÷2))÷1)=10
((5+(2+4))-1)=10
((5-1)+(2+4))=10
((5÷(1÷4))÷2)=10
((5÷(2÷4))÷1)=10
((5÷1)×(4-2))=10
((5÷1)×(4÷2))=10
((5÷1)÷(2÷4))=10
((5÷2)×(1×4))=10
((5÷2)×(4÷1))=10
((5÷2)÷(1÷4))=10
(1×((4×5)÷2))=10
(1×(4×(5÷2)))=10
(1×(4÷(2÷5)))=10
(1×(5×(4-2)))=10
(1×(5×(4÷2)))=10
(1×(5÷(2÷4)))=10
(1÷((2÷4)÷5))=10
(1÷((2÷5)÷4))=10
(1÷(2÷(4×5)))=10
(2+((4+5)-1))=10
(2+(4+(5-1)))=10
(2+(4-(1-5)))=10
(2+(5+(4-1)))=10
(2+(5-(1-4)))=10
(2-((1-4)-5))=10
(2-((1-5)-4))=10
(2-(1-(4+5)))=10
(2÷(1-(4÷5)))=10
(4×((1×5)÷2))=10
(4×((5÷1)÷2))=10
(4×((5÷2)÷1))=10
(4×(1×(5÷2)))=10
(4×(1÷(2÷5)))=10
(4×(5×(1÷2)))=10
(4×(5÷(1×2)))=10
(4×(5÷(2÷1)))=10
(4+((2+5)-1))=10
(4+(2+(5-1)))=10
(4+(2-(1-5)))=10
(4+(5+(2-1)))=10
(4+(5-(1-2)))=10
(4-((1-2)-5))=10
(4-((1-5)-2))=10
(4-(1-(2+5)))=10
(4÷((1×2)÷5))=10
(4÷((2÷1)÷5))=10
(4÷((2÷5)÷1))=10
(4÷(1×(2÷5)))=10
(4÷(1÷(5÷2)))=10
(4÷(2×(1÷5)))=10
(4÷(2÷(1×5)))=10
(4÷(2÷(5÷1)))=10
(5×((1×4)-2))=10
(5×((1×4)÷2))=10
(5×((4-2)÷1))=10
(5×((4÷1)-2))=10
(5×((4÷1)÷2))=10
(5×((4÷2)÷1))=10
(5×(1×(4-2)))=10
(5×(1×(4÷2)))=10
(5×(1÷(2÷4)))=10
(5×(4×(1÷2)))=10
(5×(4-(1×2)))=10
(5×(4-(2÷1)))=10
(5×(4÷(1×2)))=10
(5×(4÷(2÷1)))=10
(5+((2+4)-1))=10
(5+(2+(4-1)))=10
(5+(2-(1-4)))=10
(5+(4+(2-1)))=10
(5+(4-(1-2)))=10
(5-((1-2)-4))=10
(5-((1-4)-2))=10
(5-(1-(2+4)))=10
(5÷((1×2)÷4))=10
(5÷((2÷1)÷4))=10
(5÷((2÷4)÷1))=10
(5÷(1×(2÷4)))=10
(5÷(1-(2÷4)))=10
(5÷(1÷(4-2)))=10
(5÷(1÷(4÷2)))=10
(5÷(2×(1÷4)))=10
(5÷(2÷(1×4)))=10
(5÷(2÷(4÷1)))=10