Octavian became the emperor of Rome in 27 B. C. He ruled until his death in A. D. 14. How long did he rule as emperor?

When counting B. C the years go backward. For example 25 B. C would become 24 B. C. on new years. When counting A. D we're counting forward. Year 1 becomes year 2 and so forth. So knowing that what do you think?

He ruled for 40 years (January, 27 B. C until August, AD 14)