On April 17, 2025, Cliff Patrek gave a talk about “Mental Math; a former mathematics teacher in the high school level, Cliff describes that this is the 156th Talk that he has given since the late 90s. Instead of naming his book “Mental Math,” he entitled it “Don’t Slow Me Down With That Calculator.”

At times almost appearing like a magician, he shared with us a number of tricks to use when carrying out calculations without pencil or paper. But he carefully and very systematically, showed what was behind the amazing tasks he was able to carry out. He was not pretentious and obviously loved talking about this topic.

In the photograph of Cliff, he is standing next to an overhead projector, and Berghoff restaurant still had a projection screen around. He simply has not found a more recently developed projection system that allowed him to move all over the projection field, without generating an unacceptable amount of glare.