①
②
③
③()×17× 13
④
①÷×
②×3.2+6.8÷
③105×(+)
④﹣+﹣
⑤6.4÷[(3﹣1.4)×]
①0.75+ + +0.375
② +9 +99 +999 +9999
③4 -(2 + )
⑤48.3-15 -4
⑥9 ×4.25+4 ÷6