Most Question=bit manipulation, Number Theory ? Why?

I m not new on codechef and after giving like many contest only thing i consistently noticed is that out of 5 questions 4 questions are from bit manipulation, number theory, finding mex or manipulating a array? why is so?

What else do you expect from first 4 questions !?

CodeChef tries to be beginner friendly. Meaning they will give problems that can be solved in <= 5 lines of code by doing some math. This can be annoying if you are already good at coding, but be aware that Div 1 problems are mostly coding problems. Math/Number Theory/Bit Manipulation is a theme that you will see in each Division though.