The "Chibikko Soroban" series, volumes 9, 10, and 11, cover the content of levels 5, 4, and 3 respectively, making them ideal for children's arithmetic learning. - Series Name: Chibikko Soroban - Volume: 9 - Grade: Level 5 - Series Name: Chibikko Soroban - Volume: 10 - Grade: Level 4 - Series Name: Chibikko Soroban - Volume: 11 - Grade: Level 3 Thank you for viewing. I never used a soroban as a child, but I cleared these three volumes on my own as a brain training exercise as an adult. My speed is not great at all, but it was fun just to be able to work through the content of these books. I used copies of the books, so the originals are completely unmarked.