Calculate the value of 2003 multiplied by 2004 minus 2001 multiplied by 2002.

Explanation

Express the terms as (2000 + 3)(2000 + 4) - (2000 + 1)(2000 + 2). Expanding both: (2000*2000 + 2000*4 + 3*2000 + 3*4) - (2000*2000 + 2000*2 + 1*2000 + 1*2). The 2000*2000 terms cancel out, leaving (8000 + 6000 + 12) - (4000 + 2000 + 2) = 14012 - 6002 = 8010.