This little trick makes math calculations much easier.

Sources/references (March 2019)
https://twitter.com/stephens_ben/stat…
https://www.news.com.au/lifestyle/hea…
https://www.mirror.co.uk/news/weird-n…
http://www.ravimohanmishra.com/2014/0…

Updated reference June 2021
Pink Pencil Math did a video on TikTok which has over 18 million views. Definitely watch it!
https://www.popsugar.com/smart-living…
https://www.tiktok.com/@pinkpencilmat…