- Ø
**<size>**defines the size of the given number in bits.

- Ø
**<base format>**defines the type of base of the given number. For example, the number may be in binary, hexadecimal or decimal form. For this we will write “b”, “h” or “d” respectively for binary, hexadecimal and decimal format.

- Ø
**<number>**specifies the number. The number comprises of a string of characters taken from the set (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E and F).

Since it might be difficult to write and read large
number, verilog allows to place underscore (_) character in between the digits.
The underscore can be placed any where except at the first place. Underscore is ignored by the
simulator. See the example below for clarification.

**Note :**The hexadecimal alphabets (a, b, c, d, e, f) are not case sensitive. Spaces are allowed between the <size>, <base format> and <number>. The base format is not case sensitive, so it is valid to write “D” for decimal

instead of “d”.

**Example of a sized number in binary format:**

z = 4’b1100; // z is a sized four bit binary number.

**Example of a sized number in hexadecimal format:**

z = 8’hac; // z is a sized 8 bit hexadecimal
number.

**Example of a sized number in decimal format:**

z = 4’d16; // z ia sized 4 bit decimal number.

**Example of underscore to improve readability:**

z =
12’b111_101_110_101; // underscore placed
is ignored by the simulator.

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