Binary to radix12 conversion
Consider the circuit in Fig.2.21 which has a four bit binary number b3b2b1b0 as input and a five bit binary number, d4d3d2d1d0 as output.

Binary to Hex conversion

Binary to BCD conversion

Binary to grey code conversion

Binary to radix12 conversion
Can anyone explain how this circuit convert binary to radix12 conversion.
Its clear that Φ=b_{3}.b_{2} and Cin is Φ. what does the second input to adder consists of?? is it's all bits Φ or only the last bit Φ or anything else??
My doubt is clear now
Φ means nothing (we consider it as 0 or null)
So if we add number which is greater than or equal to 12 then it returns according to input
For example,
For 011 it returns as it is
12 it returns 0(0100+1100=0000)
13 it returns 1(0100+1101=0001)
14 it returns 2(0100+1110=0010)
15 it returns 3(0100+1111=0001)
@shraddhagami
where does that 0100 come from??
@dashish
b2 and b1 are given to 'And' gate
Output of 'And' Gate are given to 2nd input of first 4 input.
Ok now i see! the diagram in the question is wrong..
correct one in comment.. totally fine