All three loops variables are independent of each other, third loop always runs 6 times for( i = 1 , 2 , 4 , 8 , 16 , 32 )
second loop always runs 4 times ( b = 1 , 11 , 21 , 32 )
And first loop is similar to third one , it will run 6 times too.
Hence k will be inremented by 6 * 4 * 6 = 144 times.