Well, this depends on the number of topping ingredients you have for each serving of nachos. The general solution will be simply to add all the topping ingredients for each type. Assuming there is an average of 7 topping ingredients for every type, namely: cheese, fried beans, sour cream, onions, jalapeños, salsa, and guacamole. Hence,
Topping Ingredients = 7*256 = 1,792