Design a 4 bit BCD adder (aka mod 10, excess 10, or single decimal digit). This is like a regular 4 bit adder, but the 2 4-bit numbers (a3a2a1a0 and b3b2b1b0) it takes in are both between 0 and 9 (converted to decimal).

The output should start over after 9 though. E.g. 4+5=9, 5+5=0, 7+7=4, etc. Include a carry out for when it started over. E.g. false for 4+5, true for 5+5, 7+7. You can use anything weve talked about, including multi-bit components (like a 2-bit adder), but make sure you say what they are and you dont connect two outputs together.