A popular option at the Pizza Parlour is the 'Plus Two' pizza which is a basic cheese and tomato pizza plus a choice of any two different additional toppings from the following list: Tuna, Ham, Chicken, Onion, Mushroom, Sweetcorn. This gives 15 variations, which can be calculated as follows: Each of the six additional toppings can be combined with one of the other five to create 30 pairs, but this counts each pair twice (e.g. tuna and ham, ham and tuna).