c) The following are four uses of control accounts:
(i) To verify the arithmetical accuracy of the accounts in the ledger
(ii) To make the location of errors easier in personal accounts
(iii) The balance on the control accounts can be used in the preparation of final accounts
(iv) It is useful in checking and monitoring account officers, who may be engaging in fraudulent acts

d) The following six accounting errors cannot be discovered by means of a trial balance:
(i) Errors of omission
(ii) Errors of commission
(iii) Errors of principle
(iv) Errors of original entry
(v) Compensating errors
(vi) Errors of complete reversal