A curated list of awesome street math / mental math / guesstimation / approximate math resources
Street-Fighting Mathematics: The Art of Educated Guessing and Opportunistic Problem Solving
The Art of Insight in Science and Engineering: Mastering Complexity
Introduction to Methods of Approximation in Physics and Astronomy
Approximation Methods in Science and Engineering
Probability and Statistics Cookbook
Subtle features in projectile motion with quadratic drag found through Taylor series expansions
Universal functions - Sanjoy Mahajan
Quantifying biomolecular diffusion with a “spherical cow” model