Answer:
Let me Demonstrate this by an Example.Suppose there is Paper in the shape of Rectangle which is cut into four equal parts, and the same paper is cut into ten equal parts.
Now when the paper was divided into four parts
Ratio of one part of divided paper to ratio of whole paper
And, the second way, in which the paper was divided into ten parts
Ratio of one part of divided paper to ratio of whole paper
As, number of part of a thing increases, the size of each single divided piece decreases.
I have explained it with the help of diagram also,