①10.4÷0.4×0.25
②[0.1÷(1-0.99)-9]÷0.1
③0.99×45
④0.24×15×(3.25 - 2.35)
⑤23.2-4.6-6.8-5.4
⑥9.6×12.4-9.6-1.4×9.6