# How do you represent a negative number in Binary Coded Decimal?

All I know is that when a number is negative, you convert the decimal into binary and if it is negative you put 1111 before the binary digits.

### What is decimal to binary conversion?

"Ordinary" numbers are on base 10 (="decimal"). Binary only has 2 digits. 0 and 1 (representing "on" or "off" in some circuits). So "conversion" is how to represent an number in one to how it appears in the other. So 10 (binary) means 1x21 + 0x20 , which is 2. Decimal to binary effectively means representing an ordinary ("decimal") number in binary form. So 10 (decimal) is broken up into powers of 2 as 8+2…

### What is the binary number for the decimal number 1?

It is the same number: 1. Binary numbers are base-2, with each digit place corresponding to an exponent of 2 rather than 10 in the decimal number system. So that the number 11, which in decimal means 10 + 1, would represent 2 + 1 (3) in the binary system, which can only have the value 0 or 1 in each digit place.