=(79+1)×25
=80×25
=200063乘8加91乘63加63怎么简便=63×(8+91+1)=63×100=63001999加999乘999怎么简便360乘26加260乘64怎么简便=1000+999×（1+999)=1000+999000=1000000=360×26+26×640=26×(360+640)=26×1000=26000