In mathematical numeral systems, the base or radix for the simplest case is the number of unique digits, including zero, that a positional numeral system uses to represent numbers. For example, for the decimal system (the most common system in use today) the radix is ten, because it uses the ten digits from 0 through 9. In any numeral system, the base is written as "10". In a base ten numeral system, "10" represents the number ten; in a base two system, "10" represents the number two.
6. A BCD code that represents each digit of a decimal number by a binary number derived by adding 3 to its 4-bit true binary value is _________.
9. The application of DeMorgan's theorems to a Boolean expression with double and single inversions produces a resultant expression that contains only single inverter signs over single variables.