7203 = 3 * 7^4

7^4 is already a perfect square. You have only one 3 and if you multiply it by another 3, you will have: 3^2 which is also a perfect square.

So, the smallest number you need to multiply 7203 by is 3: 3 x 7203 ==21,609==3^2 x 7^4 - which is a perfect square.