bit is just called as binary digit To represent 2n elements, n bits are needed Here are the following Binary Codes, For example, the BCD code is otherwise called as 8421 code where the 8,4,2,1 are the weights assigned to the digits for number 3 (0011), the weightage will be 0 * 8 + 0 * 4 + 1 * 2 + 1 * 1 in 84-2-1 code, the weights are arranged like this, for example, for number 2 (0110), it is 0 * 8 + 1 * 4 + 1 * –2 + 0 * –1 similarly the same case for 2421 codes . Excess – 3 is a code which is in excess of 3 in decimal numbers . Error Detection Codes Binary information is usually transmitted from one place to other through wired medium, due to the electromagnetic radiation or external noise, the information bits can be changed (ie 1 to 0 or 0 to 1), in this scenario, there is a provision to check whether the given word or byte is correct or not. Parity bits are used for that. Odd parity or even parity is adopted based on the application, but