De Courcy, Ken: Pentertain ©1972 (circa) The Supreme Magic Co., Ltd., Bideford, England Softcover, saddle-stitched, 8x10", 14 pages

Image from Magicref

Comments: The first in a series of three books using mathematics (usually) and drawing to create entertaining and humorous stories, sometimes with a bit of magic. The other books in the series are "Son of Pentertain" and "Mistress of Pentertain"

Contents (from book):

I Introduction
1 Pentertain: how to prepare, usually done with pen and paper, but can be done on a whiteboard, etc.
2 Only Heaven - and Einstein - Knows!: a geometrical pattern and Liberals, Conservatives, and Socialists
4 Everything is Relative: number matrix prediction
5 A Not-so-Proper Charlie: Charlie's odd method of multiplying two numbers
6 The Chinese Check: another approach to the above calculation, patter would need some adjusting today
8 The Forgotten Phone Number: finding a missing number using some math
11 A Question of Degree: Charlie's job examination paper
14 A Last Word