find and calculate address in an array for given index

I Was confused for how we get the address and address calculation done in an array when we get element from array for passing an index.

So, any data structure used to achieve this mechanism? is there any mapping in memory or hashing or indexing like used in DB? 

It is simple, just like mathematical formula.

Consider one dim array ARR of N integer(2 byte memory for each element) stored in memory.

Now, to find address of ARR[i]:

Adddress(ARR[i]) = Base Address + No. Of bytes for each element * (Find index - Lower bound of ARR)

Here, 

Base Address = starting address of an array in memory
No. Of bytes for each element  = for integer, it is 2 bytes
Find index = which element you are searching in an array
Lower bound of ARR = lower bound  index of array

For Ex. consider integer array int[] ARR = new int[4];

Address	Value	Element
100	11	1st
102	12	2nd
104	13	3rd
106	14	4th

As per above table, 

Addresss(ARR[2]) = 100 + 2* (2-0) = 100+4=104

Happy Learning!!!