1999÷(1999+ 1999/2000 )+ 1/2000
=1999÷[1999*(1+1/2000)]+1/2000
=1÷[1+1/2000]+1/2000
=1*(2000/2001)+1/2000
=2000/2001+1/2000
=1-1/2001+1/2000
=1+(1/2000-1/2001)
=1+1/4002000
=4002001/4002000
1999÷(1999+ 1999/2000 )+ 1/2000
=1999÷1999+1999*(2000/1999)+1/2000
=1+2000+1/2000
0