Can anybody recommend a free program for editing spreadsheets? My old PC had excell, but it crashed and the new PC didn't come with microsoft office pre-installed.
I use Google Drive for schoolwork all the time. Its "Sheets" app is very similar to the free online version of MS Excel (which... is also free and web-based). If you don't mind something that is "almost but not quite entirely unlike" MS Excel, you could use OpenOffice. You can also try out LibreOffice, which is bundled with the version of Linux I use for porting Steam games (Linux Mint), but I have no personal experience with it.
My recommendation is Google Drive, unless you absolutely need to be sure it's compatible with MS Excel, then just use Microsoft Office Live (Google Sheets can import/export Excel spreadsheets, but going back and forth repeatedly can produce inconsistencies).
http://www.libreoffice.org/
R (http://www.r-project.org/).
:=
OpenOffice (http://www.openoffice.org/) has 100,000,000+ downloads according to the website. I used to use it before I scored free Office from work, and it works very well.
LibreOffice is an OpenOffice fork of several years. Both are great!
http://www.howtogeek.com/187663/openoffice-vs.-libreoffice-whats-the-difference-and-which-should-you-use/
Many thanks for the Recommendations.