Go to the developer tab in Excel. If you don't have it, right click on the ribbon in Excel, choose 'Customize Ribbon', check the Developer tab and click OK.

-> Go to the Developer tab -> click Visual Basic -> to Insert toolbar -> click Module ->

-> Then copy and paste the code into the window.

The custom function should work at that point.

-> When saving, you must save it as a macro enabled workbook to access the custom formula in other workbooks

Based on the formula:

BEY = [( Par value - purchase price) / Purchase price] × (365 / days to maturity)

BEY = Bond Equivalent Yield

PV = Par Value

price = Purchase Price

DTM = Days to Maturity