How can I create a workbook showing computer usage?

Not quite clear how the title (showing computer usage) relates to the issue in the post (calculate income from each day).

Normally, when you collect information like daily income, you would not enter it in the same cell and then overwrite it the next day. You'd never be able to tell which was the last amount entered, for example, or correct a data entry mistake.

The typical layout of such a scenario is to have a table with columns like

Date --- amount --- Total

You'd enter each amount in a new row and in the total column use a formula to sum the previous total with the amount of the current row, for example like

=IF(ISNUMBER(B3),B3+C2,"")

copied down.

The first row will contain your starting balance in C2, typed in.

From a list like this, you can create all kinds of overviews if you want to do reporting.

This:

adding the total, regardless of a cell being emptied then re-entered with new information

will require VBA and is not an advisable approach.

hth

Sorry for the confusion.



Let me try to make it clearer:

Objectives:

- Create a Workbook that contains the computer usage for each day they are open (11 hours) and calculating the Income (Which is located on another sheet - However when the information is removed from the system, to enter new information, the old data is lost and so, I do not know how I am supposed to calculate the total income for each day)

- The Workbook needs to be self archiving - So that, after the week is finished, I am able to have the information saved, but I will have a fresh page so I can do the next week.

I can't just ignore this because I am supposed to do it , and apparently this is easy to do on Excel WITHOUT Visual Basic, which is just frustrating me xD!

It's the last Excel task I am required to do, and I am struggling.

Is this homework?

Create a Workbook that contains the computer usage for each day they are open (11 hours) and calculating the Income (Which is located on another sheet

I don't have the full scenario, so you'll have to come up with a specific question. Post a sample workbook with what you have so far and point out where the problem is.

No, I've just been a Photoshop Junkie for so long that all other ICT Skills have gone down the drain.

My Teacher recommended that I look for projects to do, since actually putting things in real life practice is better than reading notes. So I went around my town and found a local Internet Cafe which already had a system in place, (Which was a relational database in Access) and decided to make one on Excel.
After going back to my teacher, with a specification which I created, he agreed it would be suitable for me to study with, and that all could be completed using simple formulas.

Okay, story over, here's a rough look at my current system.

http://img230.imageshack.us/img230/1706/mysolution.jpg

This is fully complete. With working validation and calculations.