"6 Hours to Master! Mental Calculation of Two-Digit by Two-Digit Numbers: Iwanami Method Ghost Mental Calculation, Elementary School Grade 3 and Up" by Kuniaki Iwanami Price: ¥857 There was a pencil mark on only one page of photo 4, but it has been erased with an eraser. I have checked to make sure I haven't missed anything, but since I've set the price to the lowest possible, I apologize if there are any remaining issues. I will sell this to those who want to challenge themselves with two-digit by two-digit mental calculation. #KuniakiIwanami #Kuniaki_Iwanami #Book #Nature/Mathematics