怎样简便怎样算99*72+78

问题描述:

怎样简便怎样算99*72+78

99*72+78
=(100-1)*72+78
=100*72-72*1+78
=7200-72+78
=7128+78=7206

100*72-72+78

99*72+78
=(99+1)*72+(78-72)
=7200+6
=7206