The following errors were detected before preparation of the trial balance. Rectify them.
(a) A sum of Rs. 5,000 written off as depreciation on buildings has not been posted to depreciation account.
(b) Payment of wages Rs. 2,000 to Venkat was posted twice to wages account.
(c) An amount of Rs. 250 for a credit sale of goods to Nila, although correctly entered in the sales book, has been posted as Rs. 200.

The following errors were located before the preparation of the trial balance. Rectify them.
(a) Paid Rs. 500 to Angappan were wrongly debited to Angannan’s account.
(b) Sale of furniture for Rs. 750 was credited to sales account.
(c) Purchase of goods from Bagya for Rs. 2,100 was wrongly passed through sales book.
(d) Wages Rs. 1,000 paid on erection of machinery were debited to wages account.

The following errors were located at the time of preparation of the trial balance. Pass rectifying entries.
(a) Goods of the value of Rs. 100 returned by Bhuvana were included in stock, but no entry was made in the books.
(b) Sale of goods to Mani on credit for Rs. 475 has been wrongly entered in the sales book as Rs. 745.
(c) A cheque of Rs. 500 received from Sandhiya was dishonoured and debited to allowances account.
(d) A sum of Rs. 300 drawn by the proprietor for personal use was debited to wages account.

Write a note on error of principle by giving an example.

What are the errors not disclosed by a trial balance?