I have assumed that the processor is using Little Endian mode. For Big Endian processors the memory will be reversed.
400 can be written in binary as
256 128 64 32 16 8 4 2 1
1 1 0 0 1 0 0 0 0
So, 2000 to 2001 will contain 10010000
2001 to 2002 will contain 00000001
and 2002 to 2003 , and 2003 to 2004 will contain all 0's
In Big Endian processors , these assignments will be reversed ,i.e , 2000 to 2001 will have all 0's
For More examples --->
https://www.quora.com/How-is-an-integer-value-stored-in-the-memory-in-C