This is a rule that should help avoid terrible blunders in complicated positions or any positions that require calculating relatively complicated variations. The rule is formulated roughly as follows. After finishing a complicated calculation, take a fresh look at the position on the board. Try to picture the position directly after the move you plan to make. Check whether you are missing something trivial. Are you perhaps losing a piece after this move? Are you missing a simple check that makes you lose material? Perhaps you will even be check mated in a few moves? Only after completing this check for terrible blunders can you now go on and make your move. We recommend our readers to include this rule in their overall method of calculation.