2018 Mathematics Calendar Hints and Errata

Thank you for your interest in the 2018 Mathematics Calendar. We've given some hints for some of the more challenging problems. Also, unfortunately, there were some formatting issues that made some problems difficult to parse and some typos. Here are the issues we know about. Please contact us if you have a question about a problem not listed below. Thanks!

Rebecca Rapoport and Dean Chung

Unfortunately, there was a typo in this one. Here's the correct problem:
Unfortunately, there was a typo in this one. Here's the correct problem:
Unfortunately, there was a small error in the image. Here's the correct image:
Unfortunately, there was a typo in this one. Here's the correct problem:
This one is actually correct but the formatting is confusing. Try to guess what we meant before you look at the correct format if you want.
This was mistranscribed to the calendar. Oops! The problem was supposed to read:
76543211234567 mod 55
Unfortunately, there was a typo in this one. It should have asked for the number of positive roots.
This was mistranscribed to the calendar and wrong. Oops! The problem was supposed to read:
but that's 14, not 28. Sorry!
This one is actually correct but the formatting is confusing. Try to guess what we meant before you look at the correct format if you want.)
Unfortunately, there was a typo in this one. It should have asked for the sum of the 1001st to 1006th digits.
Oops. That's 108. Sorry!
This was mistranscribed to the calendar. The problem was supposed to read:
There was a typo in this problem. The radius was supposed to be 16. Our apologies!
This was mistranscribed to the calendar. The problem was supposed to read:
Unfortunately, there was a typo in this one. The second number in the list should be 336, not 335.
This was mistranscribed to the calendar. The problem was supposed to read:
This was mistranscribed to the calendar. The problem was supposed to read:
Unfortunately, there was a typo in this one. The house was worth $308,000 in 1980.
This one had a typo. The interval is supposed to be [0,50] not [0,100].
The diagram was missing some important info. Here's the correct diagram:
The diagram had an extraneous 7 above the top vertex that should be ignored.