10/1*2*3*4=(12-2)/(1×2)(3×4)=3×4/(1×2×3×4)-1×2/(1×2×3×4)=1/(1×2)-1/(3×4)18/3*4*5*6=(30-12)/3×4×5×6=1/3×4-1/5×626/5*6*7*8=(56-30)/5×6×7×8=1/5×6-1/7×810/1*2*3*4+18/3*4*5*6+26/5*6*7...