It's a math based puzzle commonly known as Sudoku, the rules are that each 3x3 square can only have numbers 1-9 with no repeats, same with each 9x1 row or column. A set of numbers are placed as a starter pattern (you can solve from blank but it's significantly more challenging) and you need to fill in the remaining numbers.
It's a logic puzzle, no math is involved. It used numbers but those could be replaced with the letters 'A' through 'I' and function the same. Otherwise correct.
I started typing an angry comment about how math is logic and therefore sudoku is a math puzzle, but when I got to the second paragraph about graph theory I realized I was already losing the argument I was having with no one
Number is a simple abstraction: an exercise in conceptualizing a particular part of human experience, - the amounting of stuff and the relations of various amounts.
Its utility shines the most in the practice of measurement: determining, manipulating and comparing the amounts of stuff.
Numbers also useful as a stepping stone in a learning journey, allowing an individual mathematician to transition to using other, more powerful abstractions (like variables, polynomials, sets, functions, vectors, fields, etc.).