A friend of mine asked for my help as his Excel guru, but the problem I found is something I have never seen before, and was unable to solve, so I wondered whether anyone here would be able to help, please.

When he types a number, for instance "25", in an Excel cell which is formatted to show two decimal places, as soon as he hits enter it defaults to the fraction, rather than the whole number, so that instead of "25.00" he sees "0.25". This happens whether he selects "number" or "currency" as the cell format. Incidentally, if he selects "currency" but then opts for "none" as the currency symbol, it automatically returns to "number".

I believe he is using Office 2010.

Any ideas what is wrong and how to cure it, please?