Do not learn. Infinite series belongs to advanced mathematics and is a subject of university study. 13 belongs to the second grade of junior high school, so the IQ of 13 is 134. Advanced Mathematics (Seventh Edition) is a national planning textbook for undergraduate students of general higher education in the Twelfth Five-Year Plan, which was compiled by the Department of Mathematics of Tongji University and published by Higher Education Press. Suitable for engineering students in colleges and universities.