(2+1)(2^2+1)(2^4+1)(2^8+1)+1
=(2-1)(2+1)(2^2+1)(2^4+1)(2^8+1)+1
=(2^2-1)(2^2+1)(2^4+1)(2^8+1)+1
=(2^4-1)(2^4+1)(2^8+1)+1
=(2^8-1)(2^8+1)+1
=2^16-1+1
=2^16
=65536
2006/(2006^2-2555*2007)
=2006/(2006^2-(2006-1)*(2006+1))
=2006/(2006^2-(2006^2-1))
=2006/1
=2006