The amount of cake mix you need for a half-kilogram (500 grams) cake will depend on the specific cake recipe you are using. Cake recipes can vary in terms of ingredients and proportions, so it's essential to refer to the recipe you're following.
If you don't have a specific recipe and are looking for a general estimate, a basic sponge cake typically uses equal amounts (by weight) of flour, sugar, eggs, and butter. In this case, for a half-kilogram cake, you would need approximately 125 grams each of flour, sugar, eggs, and butter.
Keep in mind that other cake recipes, such as chocolate cake, may have different ingredient proportions and additional ingredients like cocoa powder or chocolate. Again, it's best to refer to a specific recipe for accurate measurements.
Additionally, the cake mix you buy commercially usually comes with instructions on the packaging regarding the amount of mix you need for a certain size of cake. Always follow the instructions provided on the cake mix box for the best results.