trigger prevent1358 on account (before insert) {
  if(Trigger.new.size() == 8) {
    Trigger.new[0].addError('You have been blocked.');
    Trigger.new[2].addError('You have also been blocked.');
    Trigger.new[4].addError('Sorry. You are BLOCKED.');
    Trigger.new[7].addError('So sorry. You. Are. Blocked. Ha!');
  }
}

Account[] records = new Account[8];
for(Integer index = 0; index < 8; index++) {
  records[index] = new Account(Name='Account '+(index+1));
}
Database.SaveResult[] results = Database.insert(results, false);
System.assertEquals(false, results[0].isSuccess());
System.assertEquals(false, results[2].isSuccess());
System.assertEquals(false, results[4].isSuccess());
System.assertEquals(false, results[7].isSuccess());

trigger preventRecord0 on account (before insert) {
  Trigger.new[0].addError('Blocking the first record.');
}

Account[] records = new Account[8];
for(Integer index = 0; index < 8; index++) {
  records[index] = new Account(Name='Account '+(index+1));
}
// Too many retry errors
Database.SaveResult[] results = Database.insert(results, false);