Go Back in Time and Become a God

"What's 3 times 5?" "Three five thirty five..." "Answer was wrong and you were seriously injured by three times five monsters!" "Three-five is too difficult!" … After being reborn, the protagonist finds that the world has changed. Everything must be obtained by fighting monsters, and those monsters are all difficult problems! This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.