# aiken code

The Aiken code is a BCD code in which the pseudotetrade is in the middle of the value range. The place value system of the four bits of the Aiken code represents the values 2-4-2-1, which is why this code

is also called the 2-4-2-1 code. The first decimal digits up to the decimal number

4 correspond Aiken-coded to those of the BCD code, the following 6 values form the pseudotetrade and the following five values form the digits

5 to 9. Any Aiken-coded number can be transferred to the BCD code.

The Aiken code is self-complementing, which means that swapping the 0 and the 1 gives the complement. The Aiken code thus offers advantages in the subtraction of dual numbers, which can be done by simply forming the complement of 9 and then adding. The Aiken code is named after Howard Hathaway Aiken, a professor of applied mathematics at Harvard University in Cambridge.