①
②6×+13÷8-19×12.5%
③2.84+5.6-0.84+4.4
④
-1.5 3 - 4.5 -4
0.2:0.18 17:51 :
x+50%x=7.5
①1375+450÷18×25 ②41×25%+×60-0.25
③ ④17.8-
⑤ ⑥
①103-128÷8
②1.02÷(5.2-3.5 )
③
⑤
⑥
n
0
1
2
3
4
5
6
……
2n