<p>What's a mathematical way to find all the possible combinations of 3s for 5 different toys? I would like some sort of equation or standard rule that can be applied to all problems like this, please.</p>
<p>Permutations.</p>
<p>Three spots: five choices for the first spot x 4 choices for the second x 3 choices for the third spot.</p>
<p>make 3 lines, since you have 3 spots _ _ _
the 1st spot you have 5 choices
the 2nd spot you only have 4, since one was used
and the 3rd spot you have 3
5 4 3
¯ ¯ ¯
and multiply them.. 5 x 4 x 3</p>
<p>hope that helped</p>
<p>Name them A,B,C,D,E and write out all possible subgroups.
If order of toys is not important, then:
ABC
ABD
ABE
ACD (why not ACB ?)
...</p>
<p>See a pattern?</p>