Where do you think Excel is useful and is most used: management, sales, accounting or finance?

...........>>>>>All of above OPTIONS  

Its is used in all fields but level of sophistication differes.

I think it is useful for accounting and finance more, to help them in there calculations, equations, formulas and drawing charts.

I would say accounting due to budgeting, creating balance sheets, and also preparing financial statements all support accounting functions. Mathematical calculations are involved where Microsoft excel makes it more relevant and complex to use spreadsheets. Accounting is involved with cash flow statements, profit and loss statements and also graphs and charts which are which you can create using excel from she spreadsheet data. 

In accounting, financial statement  are prepared

in finance, valuations and other analysis are done and excel make life easy

Microsoft Excel is one of the most powerful tools which can be used in the field of Accounting. In my opinion, Excel is most used in Accounting or Finance. By using the Financial Statements prepared using Excel, the Management may make appropriate decisions on the activities of the organisation.

well I believe it's the most common business software 

It's probably most vital in accounts and finance. Though as is well stated above it is used widely across all these fields.