Professor David Seff has been teaching for over four decades. In addition to number theory, he teaches calculus, geometry, algebra, probability, and statistics. In addition, he coauthored a textbook on constructive combinatorics with Dr. Earl Glenn Whitehead. In his early career, David Seff worked as an Adjunct Lecturer at City College, Baruch College, and other New York institutions. During this time, he was also employed by Chase Manhattan Bank as a Project Leader and Programmer Analyst. Using special utilities, David was able to recover data from crashed main hard drives after backup tapes had been overwritten. As a result of his expertise, the firm was spared a potential billion-dollar risk. Among other things, he upgraded and maintained Securities Tracking and Reporting Systems. David Seff received his Master's Degree in Mathematics from The Courant Institute of Mathematical Sciences in New York City. He received a Bachelor of Arts degree in Mathematics and Physics and a Master of Arts degree in History from Yeshiva University. As a freshman in college, he was selected to take graduate-level mathematics courses, as well as receiving one of the top 100 grades nationwide in the Putnam Mathematics Competition. The senior math award was nominated to him as a freshman, but he did not receive it as a senior. He worked at Guardian Life Insurance as a technical specialist and system developer. Together with many other programmers, David developed and tested the company's Y2K testing procedures. In preparation for the turn of the century, David taught other programmers new programming techniques that saved the company tens of thousands of dollars. Aside from coding new products and maintaining old stock for New Business Illustrations, David maintained insurance forms using special coding techniques to ensure six-digit precision. David Seff also taught night classes at Touro College while working for Guardian. Having worked for a life insurance firm for over a decade, David Seff returned to teaching at Kingsborough Community College and Brooklyn College. In addition to calculus, David Seff taught graduate math for secondary school teachers. Several years ago, David Seff taught a course titled "Fun with Math" with a prerequisite of "disgust" for math. It had a full enrollment and outstanding reviews. The physics courses David Seff taught also included Light, Lasers, and Optics, as well as Color, Beauty, and Light. Mathematical concepts of "Elementary Number Theory" were taught by him. He was one of only a few professors in each division to receive a faculty development grant in 1998. In addition to teaching "Non-Euclidean Geometry", he also taught "Elementary Number Theory".