Khan Academy is an American non-profit educational organization. This organization produces short educational videos, which are more similar to your every day lecture than your typical popular science video. Due to COVID-19 outbreak this educational website has opened up variety of educational content, including videos related to COVID-19 outbreak itself.
This video discusses basic intuition on how to estimate the actual cases of an epidemic outbreak. In general same methodology works for any epidemic outbreak as long as we are still in the exponential growth phase. The actual numbers are estimated for the ongoing COVID-19 outbreak and are taken from a blog post by Tomes Pueyo. We invite you to watch it.