Please help solve and explain the last part of this equation

Entries for Notes Receivable, Including Year-End Entries The following selected transactions were completed by Interlocking Devices Co., a supplier of zippers for clothing: 2017 Dec. 10. Dec. 31. Received from Unitarian Clothing & Bags Co., on account, a $42,000, 90-day, 8% note dated December 10. Recorded an adjusting entry for accrued interest on the note of December 10. Recorded the closing entry for interest revenue. Dec. 31. 2018 Mar. 10. Received payment of note and interest from Unitarian Clothing & Bags Co. Journalize the entries to record the transactions. Assume 360 days in a year. If an amount box does not require an entry, leave it blank. Assume February has 28 days in 2018 If required, round the interest to the nearest cent. 2017, Dec. 10 Notes Receivable 42,000 Accounts Receivable-Unitarian Clothing and Bags Co. 42,000 196 2017, Dec. 31-Adjusting Interest Receivable Interest Revenue 196 2017, Dec. 31-Closing Interest Revenue 196 Income Summary 106 Mar. 10. Received payment of note and interest from Unitarian Clothing & Bags Co. Journalize the entries to record the transactions. Assume 360 days in a year. If an amount box does not require an entry, leave it blank. Assume February has 28 days in 2018 If required, round the interest to the nearest cent. 2017, Dec. 10 Notes Receivable Accounts Receivable-Unitarian Clothing and Bags Co. 42,000 42,000 2017, Dec. 31-Adjusting Interest Receivable 196 Interest Revenue 196 196 2017, Dec. 31-Closing Interest Revenue Income Summary 196 2018, Mar. 10 42,000 Cash Notes Receivable Interest Receivable Interest Revenue 196