(ただし1と2を合せて12のような使い方は出来ません。)
40個の解法が見つかりました。
(((7+8)-4)-1)=10
((1+7)+(8÷4))=10
((7+(8-1))-4)=10
((7+(8-4))-1)=10
((7+8)-(1+4))=10
((7-(1-8))-4)=10
((7-(4-8))-1)=10
((7-1)+(8-4))=10
((7-1)-(4-8))=10
((7-4)+(8-1))=10
((7-4)-(1-8))=10
((8+(7-1))-4)=10
((8+(7-4))-1)=10
((8-(1-7))-4)=10
((8-(4-7))-1)=10
((8-1)+(7-4))=10
((8-1)-(4-7))=10
((8-4)+(7-1))=10
((8-4)-(1-7))=10
((8÷4)+(1+7))=10
(1+(7+(8÷4)))=10
(7+((8-1)-4))=10
(7+((8-4)-1))=10
(7+(1+(8÷4)))=10
(7+(8-(1+4)))=10
(7-((1+4)-8))=10
(7-(1+(4-8)))=10
(7-(1-(8-4)))=10
(7-(4+(1-8)))=10
(7-(4-(8-1)))=10
(8+((1+7)÷4))=10
(8+((7-1)-4))=10
(8+((7-4)-1))=10
(8+(7-(1+4)))=10
(8-((1+4)-7))=10
(8-(1+(4-7)))=10
(8-(1-(7-4)))=10
(8-(4+(1-7)))=10
(8-(4-(7-1)))=10