十萬火急!!!!!幾條數學問題!!!!!!!!!!!!!

將下列百分數化為小數:
0.21,0.05,0.0009 ,1.3 ,0.1575
將下列小數化為百分數:
47% ,60%, 1.6%,304.8%,101.5%
一條圓形跑道的半徑是14m,有人沿跑道跑了十個圈,他跑了多遠?
14x2x7/22x10
=28x7/22x10
=88x10
=880
他跑了880m

1. 21%=0.21
5%=0.05
0.09%=0.0009
130%=1.3
15又四份之三=0.1575
2. 0.47=47%
0.6=60%
.016=1.6%
3.048=304.8%
1.015=101.5%
3. (14*2)*22/7
=28*22/7
=88m

2008-08-15 23:22:38 補充：
sorry!
第3題
(14*2)*22/7*10
=28*22/7*10
=880m