This seems like a lot of extra calculations. If you want to double a recipe, just multiply all the weights by 2. If you only want to increase by 33%, multiply everything by 1.33; if you only want to increase by 23%, multiply everything by 1.23; etc. The ratios of ingredients to each other will be preserved. You don't have to calculate percentages of flour before multiplying. You're just going to multiply everything by the same factor you multiplied the flour by. The key is estimating how much to scale up. It's easy if the recipe tells you how much it makes. If a recipe makes 36 cookies and you want to make 42, multiply everything by 42/36 = 1.1666.. If you want to turn an 8 inch crust into a 10 inch crust, you need to use the ratio of the areas of the crusts--multiply everything by (pi*5*5) / (pi*4*4) = 1.5625.

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