How to find out Your Ubuntu / Debian is 32 bit or 64 bit

Some times you need to know , Your  Ubuntu / Debian is 32 bit or 64 bit,

You can use the following command

open a terminal and type

$ uname -m

You will get an output like i686  or x86_64

i686  means it is 32 Bit

x86_64  means it is 64 bit