能简算的用简便方法计算．（写出主要简便过程，无过程不得分）
①1.6×3.9×1.25      ②4.87×2.34+48.7×0.266          ③0.05×0.7×20×1.7
④2.5×3.2×12.5      ⑤3.95×7.6+3.95×3.4﹣3.95       ⑥0.49×9.9．