I have used Micorsoft Excel for more than a decade since 1997, and have loved the functionality and ease provided by the package. One of my favourite shortcut keys is F4 which repeats last action performed.
In 2008 I came across Ubuntu and alongwith it Libre Office Calc. Today when I started working with Calc, I needed the same F4 functionality, and searched whether Calc has an equivalent, and yes it has Ctrl+Shift+Y.
I plan to keep adding on this post so that over time I have all frequently used MS-Excel shortcuts equivalents in Calc on this page.