Thank you for viewing! Instant purchase is welcome☆ [About the product] Mental arithmetic training book for elementary school students. Packed with content to help you solve calculations up to 19x19 in 5 seconds. From now on, being able to do 2-digit mental arithmetic like the multiplication table will be the norm! If your calculation skills improve, your math test scores will also improve! - Title: The book that allows elementary school students to do mental arithmetic up to 19x19 in just one day - Author: Takuya Kosugi - Target age: Elementary school students - Features: Training to calculate in 5 seconds - Contents: Practice problems to improve mental calculation speed - Size: Standard book size [About the condition of the product] Purchased but hardly opened. No writing or stains. [About shipping] Will be shipped via Nekopos after waterproofing. We will offer a discount if you combine it with other items on sale. → #popopo's products are here *If you have any questions, please feel free to comment.