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jmc

prealgebra senior

Problem

How many numbers can you get by multiplying two or more distinct members of the set together?
Solution
Note that, because two or more members can be multiplied, multiplying by will only make a difference if it is one of two numbers. Thus, multiplying by adds four potential numbers.

Now, we only need to consider the number of combinations that can be made from , , , and .

Choosing two from this set offers six possiblities: , , , , , and .

Choosing three offers four possibilities: , , , and .

Finally, there is one possibility with four chosen: . Thus, there are .
Final answer
15