Office Pack for Document, Spreadsheet and Slide is the best free office software - perfect altenative Microsoft Office (Word, Excel & PowerPoint).
It's fully compatible with Microsoft Office (Word, Excel, PowerPoint & Txt), Google Docs, Google Sheets, Google Slides and OpenOffice format for Windows.
Plenty of formats supported, such as:
(.docx, .docm, .dotx, .dotm); (.doc and .dot); (.wpd); (.odt, .ott, .oth, .odm, .sxw, .stw, and .sxg)
(.xls, .xlw, and .xlt); (.xlsx, .xlsm, .xltx, .xltm); (.xlsb); (.xml); (.ods, .ots, .sxc and .stc)
(.ppt, .pps, and .pot); (.pptx, .pptm, .potx, .potm); (.odp, .odg, .otp,.sxi, and .sti)
And much more!
IMPORTANT NOTES:
Office Pack for Document, Spreadsheet and Slide does not support Windows 10 S mode. Most of all, this version of Windows is used for education (by teachers, students, etc).