Comment by ArcticCelt

7-year olds seams a bit young but Jason Roberts from Techzing through Math Academy has lead a program that got 10-year olds to get through calculus.

https://mag.uchicago.edu/education-social-service/can-fifth-...

https://outlooknewspapers.com/math-academy-multiplies-succes...

He told through the years his progress in his podcast (among other interesting things, like being one of the first developers at Uber and other fascinating stuff) https://techzinglive.com/