Floor
Smooth tile
Sealed wood or laminate
Vinyl
Low carpet
Under the rug
Nothing
Plain felt
Corner grippers
Rubber and felt pad
Push
a chair scraped back
start
Push the rug
Put it back
The grip numbers are an illustrative scale, not lab measurements. Real rugs and floors vary a lot, but the pattern holds: smooth floors need help, and a pad with a grippy side gives the most.