Packed-decimal format means that each byte of storage (except for the low order byte) can contain two decimal numbers. The low-order byte contains one digit in the leftmost portion and the sign (positive or negative) in the rightmost portion. The standard signs are used: hexadecimal F for positive numbers and hexadecimal D for negative numbers. The packed-decimal format looks like this:
The sign portion of the low-order byte indicates whether the numeric value represented in the digit portions is positive or negative. Figure 1 shows what the decimal number 21544 looks like in packed-decimal format.