Problem: A company uses both special journals and a general journal. The company accountant made the following errors during July.
Question 1. Incorrectly added the credit entries in a customer's account in the accounts receivable subsidiary ledger. The total was listed as $2,690; it should have been $2,790.
Question 2. A remittance of $400 from Don Short was correctly recorded in the cash receipts journal, but the amount was posted incorrectly to the account of customer Bill Short in the subsidiary ledger.
Question 3. A purchase of merchandise on account from Eaton Company for $1,000 was incorrectly entered in the purchases journal at $10,000.
Question 4. In the sales journal, the entries were incorrectly added for the month. The monthly total was listed as $24,820; it should have been $24,280.
How might each of the above errors be discovered?