The Applied Math & Statistics Toolkit by Morgan & Claypool bundle is now live on Humble. While not directly books about game development math, they are more on math fundamentals and that is the underpinning of game development. As with all Humble Bundles it is organized into tiers:
1$ Tier
Essentials of Game Theory
Matrices in Engineering Problems
Statistics is Easy 2nd Edition
8$ Tier
Introduction to Logic 3rd Edition
An Introduction to Proofs with Set Theory
Discrete Distributions in Engineering and Applied Sciences
Analytical Performance Modeling for Computer Systems
Probability and Statistics for STEM
15$ Tier
An Introduction to Multivariable Mathematics
C Programming and Numerical Analysis
Essentials of Applied Math for Engineers and Scientists 2nd Edition
Fast Start Advanced Calculus
Fast Start Differential Calculus
Fast Start Integral Calculus
Introduction to Statistics Using R
An Introduction to Partial Differential Equations
An Introduction to Numerical Methods for Physical Sciences
As with all Humble Bundles, you decide how your funds are allocated, between the publisher, charity, Humble and if you so choose (and thanks if you do) to support GFS using this link. You can learn more about the bundle in the video below.