Answer 1

BCD stands for binary coded division it is a way of converting decimals to binary and vice versa. well we can have it any primitive but the one popular is 0 2 4 8 16 ... in this we get the no multiply it by its place value and add to get the decimal. in binary we try to adjust them by providing left to right places. if it is normal we can simply let the decimal divide by two the base and then the reminders would the bits from unit tens etc.
binary are nothing see we use ten digits in normal life binary is a challenge of using two digits.