What is 2002 + 2004... 2050

What is 2002 + 2004... 2050


2002+2004...+2050
=(2002+2050)×25/2
=4052×25/2
=50650



2-4 + 6-8 + ····· + 2002-2004 + 2006 = equal to?


= 2*(1+3+5+7+.+1003)-2*(2+4+6+8+...+1002)
=(1+1003)*502-(2+1002)*501
=1004*502-1004*501
=1004