lg25+2/3lg8+lg20*lg5+(lg2)^2
=2lg5+(2/3)*3lg2+lg(2*10)*lg5+(lg2)^2
=2lg5+2lg2+(lg2+lg10)*lg5+(lg2)^2
=2(lg2+lg5)+lg2*lg5+lg5+(lg2)^2
=2*1+lg2(lg5+lg2)+lg5
=2+lg2*1+lg5
=2+lg2+g5
=2+1
=3