used in unsigned multiplication like - 15 * -12
we are making bit pair with multiplier bit
multiplier -12(in 6 bit 110100 ) (pairing is done in diagonal formate)
multiplier pair with meaning
0 0(assume) 0
0 0 0
1 0 -1
0 1 +1
1 0 -1
1 1 0
recoded multipler=00-1+1-10( 3 airthmatic operation require in this multiplication)