(ただし1と2を合せて12のような使い方は出来ません。)
23個の解法が見つかりました。
((1+(7+7))-5)=10
((1+7)+(7-5))=10
((1+7)-(5-7))=10
((1-5)+(7+7))=10
((7+(1+7))-5)=10
((7+7)+(1-5))=10
((7+7)-(5-1))=10
((7-5)+(1+7))=10
(1+((7+7)-5))=10
(1+(7+(7-5)))=10
(1+(7-(5-7)))=10
(1-((5-7)-7))=10
(1-(5-(7+7)))=10
(5×(1+(7÷7)))=10
(7+((1+7)-5))=10
(7+(1+(7-5)))=10
(7+(1-(5-7)))=10
(7+(7+(1-5)))=10
(7+(7-(5-1)))=10
(7-((5-1)-7))=10
(7-((5-7)-1))=10
(7-(5-(1+7)))=10