What does this symbol mean, to which topic does it belong, and how do I know more about it?

Question

What does this symbol mean, to which topic does it belong, and how do I know more about it?

Answer 1

It's long division of polynomials. In the first image you need to divide $x^2+1$ into $2x^3+x^2+3x+7$. The letter $A$ is the quotient you get, and the letter $B$ is the remainder. It might have been better (though there's nothing you can do about it) had the question used different letters to the multiple choice answers (which appear to be A, B, C and D).

The second image you're dividing $5AB$ by 11 and the quotient you get is $AB$ with remainder $10$. Of the answers we can see, only one can be right, though I would argue that the implication arrow $\implies$ is incorrect since you cannot evaluate $B$ from the long division.