①
②
③
④
⑤
⑥
① + -
② -( - )
③ - -
④ - +( - )
⑤ × +
⑥ ÷ -
①600﹣300÷20×5
②(4.8﹣3.8÷2)×0.3
③3.45×99×2+6.9
④(8+ )÷4
⑤ ÷9+ ×
⑥ ÷[ ×( - )]