Sum cells depending on number in preceding cell?

[jent]

I'm trying to develop an Excel spreadsheet that tallies the number of total hours worked on different projects.

My goal is to be able to enter in a single row the date, the project number, and the number of hours worked on that project. I'm just wondering if it's possible to have Excel look at the "Project number" column, and then assign the number of hours worked in the next column to a tally of total hours worked for that specific project.

I'm attaching screenshots of what I would want the spreadsheet to look like. The first screenshot would be what I manually type in after each day and project, and the second screenshot would be the automatically summed information.

Thanks!