Free Binary Tutorial. Binary code is a system of representing numbers, letters, commands, images and sounds. Amazingly, it uses only two types of information to do this – 1 and 0. The strings of 1’s and 0’s that make up binary code may seem random, but of course they’re not. Binary code is at the absolute heart of anything that goes on. Binary Coded Decimal (BCD) Code. Binary Coded Decimal (BCD) code is the simplest binary code to represent a decimal number. ... 10 = 0010 0111 1000. BCD code is a weighed code, that is the weight of four binary bits which represent an individual digits are 8, 4, 2, 1 modern computer perform subtraction using complements and there is a.