Alternatively, you can use the following formula instead...
In the first formula, the full calculation is always carried out before determining whether there's an error. Whereas, in the second formula, the calculation only takes place when C6 doesn't equal 0. So, technically, the second formula is more efficient.
Domenic and Jerry; Thank you both for the answers to my formula problem, all examples worked. Domenic your explanation of your example was also very helpful in helping me to understand the logic required. Thanks again