(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。
((1×2)+(1+7))=10
((1×7)+(1+2))=10
((1+(2+7))÷1)=10
((1+1)×(7-2))=10
((1+2)+(1×7))=10
((1+2)+(7÷1))=10
((1+7)+(1×2))=10
((1+7)+(2÷1))=10
((1÷1)+(2+7))=10
((2+(1+7))÷1)=10
((2+7)+(1×1))=10
((2+7)+(1÷1))=10
((2÷1)+(1+7))=10
((7+(1+2))÷1)=10
((7-2)×(1+1))=10
((7÷1)+(1+2))=10
(1×(1+(2+7)))=10
(1×(2+(1+7)))=10
(1×(7+(1+2)))=10
(1+((2+7)÷1))=10
(1+(1×(2+7)))=10
(1+(2+(1×7)))=10
(1+(2+(7÷1)))=10
(1+(7+(1×2)))=10
(1+(7+(2÷1)))=10
(2×((7-1)-1))=10
(2×(7-(1+1)))=10
(2+((1+7)÷1))=10
(2+(1×(1+7)))=10
(2+(1+(1×7)))=10
(2+(1+(7÷1)))=10
(2+(7+(1×1)))=10
(2+(7+(1÷1)))=10
(7+((1+2)÷1))=10
(7+(1×(1+2)))=10
(7+(1+(1×2)))=10
(7+(1+(2÷1)))=10
(7+(2+(1×1)))=10
(7+(2+(1÷1)))=10