How many 3-digit numbers having at least one of their digits 7

How many three digit numbers are there divisible by 7

The number of different seven-digit numbers that can be written using only the three digit 1 , 2 and 3 with the condition that the digit 2 occurs twice in each number is7C2257p2257C252None of these

1. How many numbers are there between 99 and 1000, having at least one of their digits 7?

How many 3-digit numbers can be formed with the digits 1,4,7,8 and 9 if the digits are not repeated?

How many different numbers can be formed from the digits 3, 4, 5, 6 and 7 when repetitions are allowed ?