Not possible
The smallest positive integer is 1357.
3/4 and 4/3. If you are allowed to repeat numbers, infinitely many.
358.48
-1230
1234
The smallest is 1111 if repeats are allowed. If not, it is 1235.
Using 1, 2, and 3, you can make 27 whole numbers.
The answer depends on 1357 WHAT! Since you have not bothered to share that crucial bit of information, I cannot provide a more useful answer.
2,3,5and7
add numbers or if you are allowed add punctuation.
Using the combination fuction, chose three numbers from 45 numbers. The answer is 14,190.
add them all together and then divide the answer by the number of numbers.