Enter the answer to each question in base 10. (a) If a positive integer written in base 10 has 4 digits, what is the least the integer could be? (b) If a positive integer written in binary has 6 digits, what is the most the integer could be? (c) If a positive integer has 8 digits when written in binary, at most how many digits does it have when written in base 10? (d) Find the largest number whose binary representation is exactly 4 digits longer than its base 10 representation.