原式=(100..(2004个0)-1)*(100..(2004个0)-1)+199.(2004个9)
=1000..(4008个0) -2000..(2004个0) +1 +199.(2004个9)
=1000..(4008个0)
末尾有4008个0
原式=(100..(2004个0)-1)*(100..(2004个0)-1)+199.(2004个9)
=1000..(4008个0) -2000..(2004个0) +1 +199.(2004个9)
=1000..(4008个0)
末尾有4008个0