2.用四舍五入法凑整到千分位约是2.599. .(判断对错)
: == ÷6=6÷ .
= : ==6÷ = %
9:24=3: =3÷ == %.
:100=15÷ = %==0.25= 折.
3÷ === ÷24≈ (保留两位小数)