This document describes the design of a binary coded decimal (BCD) adder circuit using a binary adder and additional logic. It explains that BCD represents numbers from 0-9 using 4-bit codes and involves adding 6 to results exceeding 9. The circuit uses a carry lookahead adder (CLA) to compute the sum and carry out of the binary addition. Additional logic checks if the sum exceeds 9, and if so add