Thank you for the opportunity to help you with your question!
Ok so :
(2 x 10^4) x (3 x 10^2)= 6 x 10^6
Now, how did I do this? All you do is you first multiple the numbers that dont have the raise to power thing (ex:10^3). Then you multiple those that do. Now 10^4 x 10^2 =10^6. Because they have same base (10) , you write the base again and just add the exponents.(4+2 in this case). SO
1)mutiply the numbers without exponents
2)Multiple numbers with exponenets
This consists of both ways youw ere taught; for example:
5^2 x 5^3=5^5
because when bases are same you leave as is, and just add exponenets.
Please let me know if you need any clarification. I'm always happy to answer your questions.