asp.net core build a matrix 5x5 and apply style

Question

Ok, what I want to do is to have a matrix 5x5, example in the picture below (ignore the text, consider just values), basically horizontal axys (a) is an array from 1 to 5 and vertical (b) the same. all the cells are results of a multiplication a*b. After that I will have a range and color cells based on the range. But I don't know from where to start. I can define two arrays for a and b but how do I view the results of a*b? I think I can define the range and apply the color on the final result