Need help with a formula

Hello,
I have a formula in a specific cell which I have created with the CONCATENATE function to define a location of interest. That formula concatenates J with the number 15 to return the result J15 as a text string.

Question: How can I use the concatenated text string result as the cell input argument for another formula in another location? I want to be able to go to another cell in my worksheet and type = and then click on the cell where I have the concatenated formula and have it use its result as the input argument. 

Thanks for the help.