At Karen's Pizza Palace there are four different toppings you can get on a pizza (all pizzas come with cheese and sauce): Onions, Strawberries, Pepperoni, and Chocolate. How many different pizzas can you order at Pete's? You can have any combination of the toppings you want including no toppings or all four toppings.
The first pizza, you have 4 choices to choose from, the 2nd pizza you have 3 choices, the 3rd you have 2 choices, and the 4th just 1 choice. So, you can order:
4! =4 x 3 x 2 x 1 = 24 number of different pizzas you can order.