Which of these numbers are natural?

a) $$2.3$$

b) $$80$$

c) $$2$$

d) $$-12$$.

### Development:

a) Can we say: "I have $$2.3$$ brothers?"" No, perhaps we have two brothers, perhaps three, but we can nothave $$2.3$$.

b) In this case you can say, for example: "In this field there are $$80$$ sheep." Therefore, it is a natural number.

c) As in the previous case, it can be used to count things, "My brother is two years old." That is to say, it is also a natural number.

d) This is not for counting objects: "Tomorrow $$-12$$ guests will visit us!" is not correct.

### Solution:

$$2.3$$ is not a natural number.

$$80$$ is a natural number.

$$2$$ is a natural number.

$$-12$$ is not a natural number.