# If 2's complement is the best way to represent numbers in computers, why worry about BCD and other binary codes?

I'm studying Digital Logic and Design. And in the first chapter, there's all this information about various binary codes. I did some searching on youtube and found this awesome video - https://www.youtube.com/watch?v=lKTsv6iVxV4&t=5s.

Now, my question is, If 2's complement is the best way to represent numbers in computers, what's the purpose of BCD?

• Its importance is mainly historical. – Yuval Filmus Jun 7 '18 at 17:02
• So, BCD is not used in any system? And numbers are only represented by 2's complement form? I'm confused because in the book that i'm studying (Digital Design by MM Mano), the information on BCD is given after the information on 2's complement representation. – Sanskar Jun 7 '18 at 17:11
• I'm not an expert, but I believe BCD is only used in legacy systems. They teach you BCD since it's in the textbook. – Yuval Filmus Jun 7 '18 at 17:29
• Okay, i get it. Thanks for responding. I can't study something when i don't know why am i studying it. I have a context now. :) – Sanskar Jun 7 '18 at 17:38
• Look for decimal floating point, quite interesting and I believe implemented in current mainframes. For operations with integers, base 10^9 or 10^18 can be useful. – gnasher729 Jun 7 '18 at 17:40