The method you use will depend on what the questions are, and
there will be some questions for which it won't be possible.
only using the numbers once
If you are not concerned with the numbers being round, then there are an infinite number of answers to this. If, on the other hand, you want to stick to round numbers, then there are very few answers: 1 * 43 -1 * -43 43i * -i -43i * i If you only want real integers, then you're down to two answers: 1 * 43 -1 * -43 And if you only want natural numbers, then there's only one answer: 1 * 43 This is because 43 is a prime number, and has no factors.
8 plus 1 , minus 5, plus 7 + 13
There are an infinitely many possible answers. Using only whole numbers you have . . . , -2 and -11, -1 and -12, 0 and -13, 1 and -14, 2 and -15, . . . You can then consider numbers to 1 decimal place and then 2 decimal places and 3, and so on etc.
== == == == == == == == == ==
The only answers are 1 and 2. Meaning 1 and 2 are the only numbers that you can divide 170 and 12 by and get whole numbers (no decimals) as answers. 170 / 1 = 170 12 / 1 = 12 170 / 2 = 85 12 / 2 = 6 Try it with any other number and you'll see that at least one of your answers will not be a whole number.
binary system
101
3! = 6.
No. Factorials can only be placed on positive whole numbers or 0. For example, 0!, 1!, and 6! are all fine, but 2.5! and (-1)! are not. Since factorials can only be placed on whole numbers, that means you will only be multiplying whole numbers. 100! = 100 * 99 * 98 ... * 1; all those numbers are whole numbers, meaning your answer will be a whole number.
12+5+5+1
0.25