Q.What is a Computerised Accounting System (CAS)? Explain the need for adopting a computerised system in place of manual accounting.

A Computerised Accounting System uses software to carry out the same recording and reporting work a manual system does, but with the mechanical steps automated.

The accounting principles applied are unchanged — only the tool used to apply them changes, since the software posts, balances and reports automatically once a voucher is entered.

A Computerised Accounting System (CAS) is a system of maintaining a business's books of account using accounting software on a computer, in place of writing entries by hand into paper journals and ledgers. The accounting principles involved — the double-entry rule, classification of accounts, preparation of a trial balance and final accounts — remain exactly the same as in manual accounting. What changes is only the tool: once a transaction is entered as a voucher, the software carries every subsequent step (posting to the ledger, balancing accounts, drawing up reports) forward automatically.

Why a computerised system became necessary:

1. Volume. As a business grows, the number of daily transactions grows with it. A manual clerk can process only a limited number of entries accurately in a working day, while a computer can post large volumes within seconds.
2. Repetition. Posting the same transaction to two or more accounts under double entry is repetitive, mechanical work that a computer performs faster and with far fewer slips than manual copying.
3. Speed of reporting. A trial balance or set of final accounts that might take a manual bookkeeper days to prepare and check can be generated by software almost instantly, whenever it is needed rather than only at a fixed period-end.
4. Multiple users. Several branches or departments can record transactions into one shared computerised system simultaneously — something a single physical ledger book cannot support.

A computerised accounting system was therefore adopted not to change what accounting requires, but to remove the slow, repetitive and error-prone parts of applying accounting rules at the scale a modern, growing business operates at.