两条直线相交成45°的角,用一个2倍放大镜看这两条直线,它们就互相垂直. .
:24=0.25==3÷ = %
÷25==33: = %.
1:8== %= (小数)
=0.4= ÷10=10: = %
26: == %=六成五= (注:此括号填小数)