I think "The sum of the parts" challenge problem (Apr - June 2006) contains an error:
18 has also 6 and 3 as a factors resulting in 1+2+3+6+9 and not 1+2+9

Analistul,

Good catch! I agree that this particular part of the explanation is in error; fortunately, it does not affect the overall answer of the problem, since 1 + 2 + 3 + 6 + 9 does not equal 18.

The anwer to the problem is still E, but I will be certain to forward this oversight to the powers that be.

Thanks!
-dan

Where can we find these "Challenge problems"

Thanks

Where can we find these "Challenge problems"

Thanks

Our challenge problems used to be open to the public but we now save them for our students only. :) If you are enrolled in one of our courses or if you purchased access to the challenge problems, you can find them on the private part of the web site when you log in.