1. A local creperie offers sweet crepes and savory crepes. A sweet crepe could have any fruit (banana, strawberry, mango, apple, lemon) and any syrup (nutella, chocolate, caramel, honey). A savory crepe could have any vegetable (broccoli, mushroom, spinach) and any protein (turkey, cheese, prosciutto). How many different crepes are on the menu?
2. Prove that every binary number n that ends in 0 is even.