计算下面各题，能简便的要用简便方法算。

①32×2.5×1.25

②5.56×0.45+5.56×0.55

③0.375÷0.25×4

④68.5÷25÷0.4

⑤15.8-4.9÷2

⑥2.7×[（3.2+6.8）÷0.25]