根号5等于2.236根号10的负2次方乘3.2=√(10^(-2)*3.2)=√(3.2/100)=√(320/10000)=√(64*5/10000)=√64*√5/√10000=8*2.236/100=0.17888（2）根号2.7=√(30*9/100)=√30*√9/√100=3*5.477/10=1.6431...