The book “Stories about mathematics with examples in Python and C” is presented to the attention of readers. The book describes various stories or problems directly or indirectly related to mathematics (magic squares, prime numbers, etc.). More complex issues are briefly discussed, such as performing calculations using the GPU. The book is distributed free of charge, you can download the latest version in PDF at Text version 1.10. Contents:- Mathematical tricks- Pi number- Calculating the radius of the Earth- Can the Earth be flat?- Prime numbers- Perfect numbers- Magic square- Magic square from prime numbers- Fibonacci numbers - Pitch of notes - Rotation of planets - Paradoxes of probability theory - Surface of the Moon - Are random numbers really random? - Distribution of random variables - Measuring the speed of light - Can you see the past with your own eyes? - How many volts are in the electrical network? - Neural networks - Use TensorFlow libraries - Fractals - Gabriel's Horn - Graphing functions - Accuracy of computer calculations - Mathematics and calendar - Is it possible to win at gambling? - Pythagorean theorem - ABC hypothesis - Appendix 1 - Calculations using a video card, example - Appendix 2 - Language speed Python - Appendix 3 - Example of program optimization - Appendix 4 - Testing a program in Fortran-90