$~~~~ \underbrace{222···22}_{2000個(gè)2}×\underbrace{999···99}_{2000個(gè)9}$
$=\underbrace{222···22}_{2000個(gè)2}×(1\underbrace{000···00}_{2000個(gè)0}-1)$
$=\underbrace{222···22}_{2000個(gè)2}×1\underbrace{000···00}_{2000個(gè)0}-\underbrace{222···22}_{2000個(gè)2}$
$=\underbrace{222···2}_{1999個(gè)2}1\underbrace{77···7}_{1999個(gè)7}8$