To do this, you only have to run on any terminal commands that you indicated below:
Step 1) Open a terminal Linux / Ubuntu with Ctrl + Alt + T keys or by clicking Applications -> Accessories -> Terminal
Step 2) Executes any of the following commands:
$ Grep -w lm / proc / cpuinfo
Where if the letters "lm" are not red means that your processor is 32 bits. If the letters "lm" If they are red means your processor is 64 bits.
$ Sudo lshw -class cpu | grep width
$ Sudo lshw | grep "description: CPU" -A 12 | grep width
Directly where you get a 32 or 64 that will indicate whether your processor is 32 or 64 bits respectively.
Step 3) Remember that if your processor is 32-bit version of both the operating system and programs you are going to install must be 32 bits. However, if your processor is 64-bit version of the operating system or programs you are going to install can be both 32 and 64 bit but it is recommended to be 64-bit to maximize the capacity of your processor!