"Books to Improve Elementary School Students' Academic Ability: Titled "Latest Two-Digit Mental Calculation Methods" Taught by Popular University of Tokyo Students! Mental calculation for 3-digit ÷ 2-digit Mental calculation for 2-digit × 2-digit A set of 3 books in total. There are no markings, but please purchase with the understanding that they have been stored for a long period. #Books #Lifestyle/Household Management"