Question

If two sets $A$ and $B$ are having $39$ elements in common, then the number of elements common to each of the sets $A\times B$ and $B\times A$ are

• A. $2^{39}$
• B. ${39}^2$
• C. $78$
• D. $351$

Answer 1

The correct option is B ${39}^2$

If set $A$ and set $B$ have $39$ common elements, then the number of common elements in set $A\times B$ and set $B\times A={39}^2$