Release That Witch
Cheng Yan travels through time, only to end up becoming an honorable prince in the Middle Ages of Europe. Yet this world was not quite as simple as he thought. Witches with magical powers abound, and fearsome wars between churches and kingdoms rage throughout the land. Roland, a prince regarded as hopeless by his own father and assigned to the worst fief, spends his time developing a poor and backward town into a strong and modern city, while fighting against his siblings for the throne and absolute control over the kingdom. Join Roland as he befriends and allies with witches and, through fighting and even farming, pushes back invaders from the realm of evil.
Roland went back to his office so he could continue writing down the basic mathematical knowledge he had in his mind after dinner.
He did not have an extraordinarily retentive memory, not to mention his memory would decline over time. Due to his profession, mathematics and physics were the most frequently used subjects, while his information about history, geography, biology, chemistry and so on had degenerated to an entry-level. Thus, regardless of its usefulness, it was better for him to take notes about everything in order to retain more knowledge.
After he finished each page he would have Scroll commit it to memory. All she had to do was look over the page and it was permanently recorded. Unfortunately, Scroll's ability only extended to the memory of looking at the information and she could not teach herself junior-high-school mathematics. So, Roland explained it to her when he was free.