The word "mnemonic" means a tool or technique that helps us remember things easily. It is something like a trick or shortcut that assists our memory, making it easier to recall or learn information. Full definition
Outlier memory is often the result of using mnemonic devices rather than a natural capacity. (geekwrapped.com)
On a marginally related topic, in the category of mnemonics for things, one way to remember the radius of the Earth is as 20 / π Mm (1 Mm = 1000 km), namely 6.3662. (judithcurry.com)
starter and a skimming and scanning relay race, full lesson plan and power point, all resources and a new mnemonic for remembering what to look out for when scanning a text. (tes.com)