（1）原式=8.4×（0.98+0.02）

                =8.4×1

                =8.4（2）原式=8.56+8.8÷32

                =8.56+0.275

                =8.835

（3）原式=0.8×0.68÷0.01

                =0.544÷0.01

                =54.4（4）原式=（1.2+1.3）×0.4

                =2.5×0.4

                =1