For to know how works this technique, I’m going to do 10 hours classes of soroban and flash anzan with the world’s foremost mental math expert: Jeonghee Lee (record in memoriad of flash anzan, división, 10x10 additions, multiplication).
JEONGHEE LEE IS THE ONLY KNOW SOROBAN ABACUS MASTER TO HAVE REACHED THE ELEVENTH DAN!!!.
I need two persons more for to do the classes with 60 % of disccount.
Read announcement of this here (I put videos of her also):