February 2021
Problem of the Month

Prime Clock

Leave six adjacent numbers of the face of a clock intact and rearrange the other six in such a way that the sum of every pair of ajacent numbers is a prime.

Solution to the Problem:

The numbers in black are the six adjacent numbers left intact (11, 12, 1, 2, 3, 4).
The numbers in red are the ones rearranged (5, 6, 7, 8, 9, 10).
The primes formed beginning with 12 and going clockwise are:
13, 3, 5, 7, 11, 17, 19, 17, 13, 11, 17, and 23.



Veena Mg, Ivy Joseph, Brijesh Dave, and Katherine Grossman sent in a different solution:

Correctly solved by:

1. Veena Mg	Bangalore, Karnataka, India
2. Colin (Yowie) Bowey	Beechworth, Victoria, Australia
3. Rebecca Austin	Kosciusko, Mississippi
3. Ivy Joseph	Pune, Maharashtra, India
4. Brijesh Dave	Mumbai City, Maharashtra, India
5. Melih Karabıyık	Kayseri,Turkey
6. Katherine Grossman	Redlands Middle School Grand Junction, Colorado

Send any comments or questions to: David Pleacher