Spreadsheet Programs

LibreOffice is another option. It has a lot more updates than OpenOffice. However, you must use an older version of LibreOffice v6.x since support for macOS 10.11 was dropped with later releases:

https://downloadarchive.documentfoundation.org/libreoffice/old/6.4.7.2/mac/x86_64/LibreOffice_6.4.7.2_MacOS_x86-64.dmg

[This is a Direct Download Link]

Two to consider:

Open Office https://www.openoffice.org/

Apple Numbers