19, 28, 37, 46, 55, 64, 73, 82, 91
There can be no answer to the question. A 3-digit number is an integer between 100 and 999 (inclusive).
There is no number. 100 is the only one that has a hundreds digit. It's impossible.
There are no 3-digit whole numbers whose digits sum to 3. The smallest 3-digit number is 100, and the largest is 999, but in neither case is the sum of the digits equal to 3.
Seven of them.
46
There are 8 numbers between 100 and 200 (inclusive) that have a digit sum of 12, namely: 129, 138, 147, 156, 165, 174, 183, 192.
930
123
There are nine of them. They are:108117126135144153162171180
Since we are talking for the sum of digits, then we are talking about 2-digit numbers between 1 and 100, which are 90 numbers (10 to 99). From these numbers only half of them satisfy the above condition, that is 45 numbers. So 50% of 2-digit numbers between 1 and 100 have an odd sum of their digits.
There are 5460 five digit numbers with a digit sum of 22.
27