
 Rate Projections Functions Walkthrough
 Accruals and Cash
 Repeating Formulae
 Range Names and References
 Optional Parameters
 Using PmtsPerYear
 Modelling Seasonality
 Calculating Interest
 Using Business Functions in VBA (Visual Basic for Applications)
 Array Functions
 Volatility
 Annual Equivalent Rates
 Array Function
 Auto Multi Functions
 Variable Plurality
 GoalSeek
 Press the F2 key. This highlights the input cells to the function. Do any of them look odd? If they have errors (i.e. NUM!) this is cause in error in your function.
 With a NUM! cell highlighted, select the Trace Facility from the BF menu. Look at the first few statements. Is it reporting an error? It almost certainly is. If so, it will tell you which variable is in error, and why. If you don"t see the error there, look further on in the Trace output. If there is an error thrown up by the function itself (i.e. the calculations) this will show up later in the Trace output.
 With the NUM! cell highlighted, Press AltI F (insert function). This does not insert a function, actually, but brings up the Excel function wizard. Here you can see each of your input variables evaluated one by one. Do they all calculate OK? Any errors in the inputs? Any range names pointing to ranges that don"t exists? Are there any nonsensical dates?
 Count the number of arguments in your function. Do they match the required number for the function?
 If you still have problems, load the example spreadsheet for that function  the easiest way to do this is through the Quick Reference. One by one, change the argument values so that they match your problem case. You should see when you have found the argument that is giving the problems.
 Are you sure the function exists? Go AltI F to bring up Excel"s function wizard. Does the function Wizard recognise the function and show you each of its arguments?
 Activate the BF Selector. Is the function you require listed?
 Bring up an example of the function using the Quick Reference
How To Isolate The Cause of a Errors in Cells using Trace  
NUM! Errors NUM! Errors occur when a function fails for any reason i.e. it cannot successfully complete its calculations. This is our recommended procedure for finding the cause of the error: NAME? Errors A NAME? error means that Excel can"t find the function. 