The fertilizer numbers, which are always in the same order (N-P-K), tell you how much nitrogen, phosphorus, and potassium are in the fertilizer. They may be whole numbers or decimals and might be the same number, like 10-10-10, but often are three different numbers. Itâ??s even possible to have one or two of the numbers be zeros. The numbers are a percentage of how much of each nutrient is in the fertilizer. Since the numbers are a percentage by weight, the higher the number, the more of that nutrient there is in the fertilizer. A 20-20-20 fertilizer has twice as much NPK in it as a 10-10-10 fertilizer.