（ただし１と２を合せて１２のような使い方は出来ません。）
58個の解法が見つかりました。
((2×4)×(5÷4))=10
((2×4)÷(4÷5))=10
((2×5)×(4÷4))=10
((2×5)+(4-4))=10
((2×5)-(4-4))=10
((2×5)÷(4÷4))=10
((2÷4)×(4×5))=10
((4×(2×5))÷4)=10
((4×5)×(2÷4))=10
((4×5)÷(4-2))=10
((4×5)÷(4÷2))=10
((4+(2×5))-4)=10
((4-4)+(2×5))=10
((4÷4)×(2×5))=10
((5×(2×4))÷4)=10
((5÷4)×(2×4))=10
(2×((4×5)÷4))=10
(2×((4+5)-4))=10
(2×(4×(5÷4)))=10
(2×(4+(5-4)))=10
(2×(4-(4-5)))=10
(2×(4÷(4÷5)))=10
(2×(5×(4÷4)))=10
(2×(5+(4-4)))=10
(2×(5-(4-4)))=10
(2×(5÷(4÷4)))=10
(2÷((4÷4)÷5))=10
(2÷((4÷5)÷4))=10
(2÷(4÷(4×5)))=10
(4×((2×5)÷4))=10
(4×(2×(5÷4)))=10
(4×(2÷(4÷5)))=10
(4×(5×(2÷4)))=10
(4×(5÷(4-2)))=10
(4×(5÷(4÷2)))=10
(4+((2×5)-4))=10
(4-(4-(2×5)))=10
(4÷((4-2)÷5))=10
(4÷((4÷2)÷5))=10
(4÷((4÷5)÷2))=10
(4÷(4÷(2×5)))=10
(5×((2×4)÷4))=10
(5×((2+4)-4))=10
(5×(2×(4÷4)))=10
(5×(2+(4-4)))=10
(5×(2-(4-4)))=10
(5×(2÷(4÷4)))=10
(5×(4×(2÷4)))=10
(5×(4+(2-4)))=10
(5×(4-(4-2)))=10
(5×(4-(4÷2)))=10
(5×(4÷(4-2)))=10
(5×(4÷(4÷2)))=10
(5÷((4-2)÷4))=10
(5÷((4÷2)÷4))=10
(5÷((4÷4)÷2))=10
(5÷(4÷(2×4)))=10