5.3乘以99加5.3,12.5乘以35乘以25,13乘以2.5乘以0.8加3.6,19分之5减17分之4加19分之14减17分之13要用简便方法

5.3*99+5.3=5.3*(99+1)=5.3*100=53012.5*35*25=12.5*(8-1)*(4+1)*25=(100-12.5)*(100+25)=10000+2500-1250-312.5=10937.513*2.5*0.8+3.6=13*(2.5*0.4)*2+3.6=13*2+3.6=36+3.6=39.65/19-4/17+14/19-13/17=(5/19+14/19...