Actually,i can't understand the union and

intersection thing in venn diagram !!!!

Venn diagrams are diagrams that show possible relations between finite collections of sets. Venn diagrams represent the elements of the set normally using circles. Venn diagram is a picture that is used to illustrate unions, intersections and other operations on sets.

When you are asked to find the number which is given by Either A or B, then you have to use concept of union i.e. you have to represent the whole diagram as shown in the following figure.

In case when you are asked to find the number which is given by both A and B, then you have to use concept of intersection i.e. you have to represent only that part which is common in both as shown in the following figure.

Hope you will get it now!