First, I am a non-computer savvy person switching from Windows 7 to a MacBook Air with El Capitan. I have MS Excel 2013 on my Windows 7 machine, and use it to run a personal finance worksheet. Second, I have mentally been trying to figure if I want to keep the Excel capability or try to switch to Numbers. My needs are small; mostly just like the fact that Excel has freeze panes. In the Mac shopping process, I took along a USB stick and discovered that the Mac would "read" my Excel spreadsheet. Thought that was neat. Next someone somewhere said that Numbers would "freeze" headers and such, but only up to five deep (whatever that means). Today I visited a friend with my Windows 7 machine to sort out errors in my Excel spreadsheet. While there I pulled out my Mac (he just got one at work), and we discovered that it looks like I can change data and basically maintain my Excel spreadsheet on the Mac. If so, perhaps this would obviate my need to devote endless hours converting my spreadsheet to Numbers or to pay for Excel for the Mac. I have been suffering under the illusion (?) that the Mac would not do anything more than allow me to look at my Windows-based Excel spreadsheet. My questions are as follows. Can the Mac really allow me to run my Windows Excel spreadsheet all by itself? Is it El Capitan doing this or Numbers? If I can use my Mac to maintain my current Excel spreadsheet, can I somehow use the Mac to build additional spreadsheets with my 2013 MS Excel? Again, I have been under the understanding that the Mac OS and Windows OS were two different things relative to programs they run. I am sure I will have more questions on this subject, but want to get the ball rolling. Appreciate any education I can get! Edit: Hope I have come close to the correct sub-forum for posting this. If not, perhaps a moderator could kindly move it.