How are you to find 2007^2 − 2006^2 without a calculator?

Like with many questions in the PAT test once you know what to do it is quite easy! To solve you can use a difference of two squares i.e. (2007-2006)(2007+2006). As the first bracket gives 1 and the second gives 4013 (by arithmetic). Therefore you get 4013*1 = 4013