The three number forms exist for interaction between computers and people. There is no difference in the representations of the integers inside the computer. The decimal form is the most natural for people. However, the octal and hexadecimal forms provide a convenient way to control or see the binary number pattern. There is no way to directly enter a binary form. For a further description of the representation of binary forms using octal and hexadecimal, see this link.

The notation that is used to represent the three forms is shown in the table below. This table is also in IDL Help.