The paying teller must be sure before cashing a check that the depositor (who is the drawer) has sufficient money in the bank to pay it. Otherwise, theoretically at least, the bank should not pay it. Sometimes, however, banks will, in the case of good customers, make an exception, and allow an "overdraft," which occurs when the bank pays a check drawn for a larger amount than the drawer has to his credit. Overdrafts are discouraged by all banking authorities and a bank habitually permitting them will probably be censured by the National or State examiners. A bank is not bound to pay a part of a check where there is not enough to the depositor's credit to pay it in full. Suppose A has $1,000 in the bank, and draws two checks for $600 each. The bank is bound to pay the first one presented, even though it may have been drawn later than the other one, and the bank will not have to pay the latter when it is presented, since the account would then be overdrawn. Nor would it have to pay $400 on the second one presented. Suppose the two $600 checks A has drawn are presented at the same time. If both are paid the account will be overdrawn. In cases of simultaneous presentation, the bank's officers can legally select the one they prefer to pay.