Microsoft Excel is one of the most popular program with over a billion users. It is being used for creating charts, tables, reports, identifying trends, and arranging data, etc. Though, it comes with some brilliant functions that enhances productivity and after learning some useful tricks anyone. Popular Alternatives to Microsoft Office Excel for Mac. Explore 24 Mac apps like Microsoft Office Excel, all suggested and ranked by the AlternativeTo user.
If you just need to view an Excel spreadsheet (.xls or.xlsx extension), you may be surprised to learn that Preview in Mountain Lion (and Lion, possibly?) can open and display them quite competently. You won't be able to edit anything, and I'm sure there may be problems with more advanced functions and macros and such, but if you just want to quickly view or print a spreadsheet, it may do the job. Numbers, part of Apple's iWork suite, is neither free nor lightweight. But at US$20, it's quite affordable, particularly in proportion to the functionality it provides, and it certainly feels more lightweight than Open/LibreOffice.
Update 7 Feb 2018 (since this post seems to have got some attention recently for some reason): Numbers is now free in the Mac App Store and has been for some time. If Preview isn't doing the job or you do need to edit the spreadsheet, give it a try.