一个数由5个亿、5个千万、9个万、7个百组成,这个数是 ,省略亿位后面的尾数约是 .
=15÷ = :50=.
1.5: =0.75=75÷ = :36=.
:12=5÷4== %= (填小数).
3÷4=9: == 填分数= (填小写)
9: =0.75==21÷ = :4.