Find number and size of physical Memory in a host

Open a putty session and become an admin user.

type the following:

dmidecode | grep "Size"

You will get the following output:

Runtime Size: 57104 bytes
                ROM Size: 4096 kB
                Installed Size: 32 KB
                Maximum Size: 32 KB
                Installed Size: 4096 KB
                Maximum Size: 4096 KB
                Installed Size: 32 KB
                Maximum Size: 32 KB
                Installed Size: 4096 KB
                Maximum Size: 4096 KB
                Size: 4096 MB
                Size: 4096 MB
                Size: 4096 MB
                Size: 4096 MB
                Size: No Module Installed
                Size: No Module Installed
                Size: No Module Installed
                Size: No Module Installed
                Range Size: 16 GB
                Range Size: 8 GB
                Range Size: 8 GB
                Range Size: 8 GB
                Range Size: 8 GB
                Range Size: 1 kB
                Range Size: 1 kB
                Range Size: 1 kB
                Range Size: 1 kB

The highlighted section gives you the slots and DIMMs installed, in this case 4 x 4GB = 16GB.