用简便方法计算如下：
5.4×0.68+6.8×0.46
=5.4×0.68+0.68×4.6
=（5.4+4.6）×0.68
=10×0.68
=6.8
5.4×0.68+6.8×0.46=0.54×6.8+6.8×0.46=（0.54+0.46）×6.8=1×6.8=6.8
