a=0.125e-1997 b=8e-2001=0.0008e-1997a+b=(0.125+0.0008)e-1997=0.1258e-1997a-b=(0.125-0.0008)e-1997=0.1242e-1997a×b=0.125*8*10^-1997*10^-2001=1e-3998a÷b=0.125/8*10^-1997/10^-2001=0.125/8*10^(2001-1997)=1250/8=156.25好好看科学计数法