（1）原式=16.8-6.8×0.25

                =16.8-1.7

                =15.1（2）原式=0.25×40×6.5

                =10×6.5

                =65

（3）原式=0.25×4×（8×1.25）

                =1×10

                =10（4）原式= 4.672+9.36

                =14.032

（5）原式=（10+0.1）×0.99

                =9.9+0.099

                =9.999（6）原式= 4.66×（0.28+0.82-1）

                = 4.66×0.1

                =0.466