A Cardinal number represents an equivalence class of sets between which there is a bijection (one-to-one correspondence). It is the number of elements in any member of the equivalence class. An Ordinal number represents an equivalence class of well-ordered sets between which there is an order-preserving bijection. It is the number of elements in any member of the equivalence class. The difference is only in whether the sets are ordered.
It is the basis for protein manufacture in plants and plays a major part in photosynthesis. For lawns, shrubs and leafy houseplants, a nitrogen-rich fertilizer is the best choice. When reading a fertilizer package, nitrogen will be the first in a series of numbers appearing with dashes between them. For example, a formula of 10-0-0 is a nitrogen-only fertilizer.
Many hobbyists recommend a balanced fertilizer, with all three main ingredients, something akin to 20-20-20 or 20-10-10. These numbers refer to the three most common trace elements that all plants need: nitrogen, phosphorus, and potash.herefore, the higher the numbers, the more expensive the fertilizer, per unit, and the less of it you need to treat a given area. The main point is that when someone recommends 20-10-10 and you can find only a 10-5-5 fertilizer, other than perhaps price, there may be no difference.