what does it mean when someone says 10 fold
Fold change Fold change is so-called as it is common to describe an increase of multiple X as an "X-fold increase". As such, several dictionaries, including the Oxford English Dictionary[1] and Merriam-Webster Dictionary,[2] as well as Collins's Dictionary of Mathematics, define "-fold" to mean "times," as in "2-fold" = "2 times" = "double." Likely because of this definition, many scientists use not only "fold" but also "fold change" to be synonymous with "times", as in "3-fold larger" = "3 times larger."[3][4][5]. More ambiguous is fold decrease, where for instance a decrease of 50% between two measurements would generally be referred to a "half-fold change" rather than a "2-fold decrease".