①3.14×7.2+3.14×2.8
②9.9×99+9.9
③58×9.9
④12.5×32×2.5
⑤2.9×102
①0.42×15=
②5.2×0.8=
③1.37×0.21≈(得数保留一位小数)
④2.16×8=