How many 4 digit numbers can be formed by using 0 , 1 , 2 , 3 , 4 , 5 , 6 , and 7 ? How many of them are between 4000 and 6000 ?
Using the numbers 0 , 2 , 4 , 5 , 6 and 7 , how many 3 digit numbers can be formed ?