\(1992\times19911991-1991\times19921992\)
\(=1992\times1991\times10001-1991\times1992\times10001\)
\(=0\)
\(1992\times19911991-1991\times19921992\)
\(=1992\times1991\times10001-1991\times1992\times10001\)
\(=0\)
TACH 2 H :
1992 NHAN 19911991= 1992 NHAN 1001 NHAN 1991
1991 NHAN 1992 NHAN 1001
TA CO:1992 NHAN 1991 NHAN 1001 -1992 NHAN 1991 NHAN 1001=0