Math CentralQuandaries & Queries


Question from Kats, a student:

How Many sub sets are in set k={6,7,3}

Hi Kats,

Suppose you want to list all the possible subsets. Start with the element 6. You can start a subset by including 6 or not including 6. Thus there are $2$ subsets started,

  1. $\{6$ and

  2. $\{$

I haven't put in a closing $\}$ since I haven't completed building the subsets yet.

Now look at the element 7. I can continue each of the subsets I have started by including or not including 7. Thus at this point I have started $2 \times 2 = 4$ subsets,

  1. $\{6, 7$

  2. $\{6$

  3. $\{7$ and

  4. $\{$

Finally the last element 3. Again you can build on each of the $4$ subsets you have started by including 3 or not including 3. Now you can put in the closing $\}$ as the building is complete. How many are there? Can you list them all?

Write back if you ned more assistance,

About Math Central


Math Central is supported by the University of Regina and the Imperial Oil Foundation.
Quandaries & Queries page Home page University of Regina