What is the answer of these questions?

What is the answer of these questions? How many numbers greater than 3000 can be formed from (0, 1, 2, 4, 5), each number cannot be used more than once a number of 8 bits starting with the first 2 bits 11 and the last 2 00 how many combinations? how many even number are there in a 2 digits number? 20 questions of true or flase, how many answers can the student answer? (2^20) How many numbers less than 4000 can be formed from (numbers I guess 6 numbers)