# I'd like to discuss this Venn Diagram

Question:

For each $$n \in \mathbb{N}$$ be $$D_n = (0, {1 \over n})$$, where $$(0, {1 \over n})$$ represents the open interval which extremes are $$0$$ and $${1 \over n}$$. Define the difference between $$D_3 - D_{20}$$

My solution:

I tried to put the sets in a Venn Diagram to make it clear but sincerely i got even more confused.

• If you want a diagram, then some scattered fractions aren't the way to go. $D_n$ is an interval. Draw the interval $D_3$ and the interval $D_{20}$; do you understand what these two sets are individually?