DRUG CLASS AND MECHANISM: Rosuvastatin is an oral drug for lowering blood cholesterol levels. It belongs to a class of drugs called HMG-CoA reductase inhibitors, more commonly referred to as  statins ..RUG CLASS AND MECHANISM: Rosuvastatin is an oral drug for lowering blood cholesterol levels. It belongs to a class of drugs called HMG-CoA reductase inhibitors, more commonly referred to as  statins ..
Natural numbers are naturally used for counting apples (and other things) so they are sometimes called counting numbers. Even some animals other than humans can count and add, so they must be natural. Minus two apples isn't very natural so negative numbers are not included.
You can add two natural numbers together, and you will always get another natural number, as in the famous fact that one and one are two. Subtraction, on the other hand, is trickier. If you subtract a number, for example the number 5, from itself, you get something new, something that is not a natural number at all. We call it the number 0 or zero. And if you subtract a number, again say 5, from a smaller number, say 3, then you get something else that is new, namely a negative integer, which in this case is -2, called minus two.