Forgot password? New user? Sign up
Existing user? Log in
Problems of the Week
Contribute a problem- Week of December 17
- Week of December 10
- Week of December 3
- Week of November 26
- Week of November 19
- Week of November 12
- Week of November 5
- Week of October 29
- Week of October 22
- Week of October 15
- Week of October 8
- Week of October 1
- Week of September 24
- Week of September 17
- Week of September 10
- Week of September 3
- Week of August 27
- Week of August 20
- Week of August 13
- Week of August 6
- Week of July 30
- Week of July 23
- Week of July 16
- Week of July 9
- Week of July 2
- Week of June 25
- Week of June 18
- Week of June 11
- Week of June 4
- Week of May 28
- Week of May 21
- Week of May 14
- Week of May 7
- Week of April 30
- Week of April 23
- Week of April 16
- Week of April 9
- Week of April 2
- Week of March 26
- Week of March 19
- Week of March 12
- Week of March 5
- Week of February 26
- Week of February 19
- Week of February 12
- Week of February 5
- Week of January 29
- Week of January 22
- Week of January 15
- Week of January 8
- Week of January 1
- Week of December 25
- Week of December 18
- Week of December 11
- Week of December 4
- Week of November 27
- Week of November 20
- Week of November 13
- Week of November 6
- Week of October 30
- Week of October 23
- Week of October 16
- Week of October 9
- Week of October 2
- Week of September 25
- Week of September 18
- Week of September 11
- Week of September 4
- Week of August 28
- Week of August 21
- Week of August 14
- Week of August 7
- Week of July 31
- Week of July 24
- Week of July 17
- Week of July 10
- Week of July 3
- Week of June 26
- Week of June 19
- Week of June 12
- Week of June 5
- Week of May 29
- Week of May 22
- Week of May 15
- Week of May 8
- Week of May 1
- Week of April 24
- Week of April 17
- Week of April 10
- Week of April 3
- Week of March 27
- Week of March 20
- Week of March 13
- Week of March 6
- Week of February 27
- Week of February 20
- Week of February 13
- Week of February 6
A hollow cylinder is completely filled with frozen water.
Will it take longer to roll down an inclined plane while it’s frozen, or after it melts?
Assume: When frozen, the water does not move relative to the cylinder.
by
Pranshu Gaba
Are you sure you want to view the solution?
What is the fewest number of colors needed such that no two adjacent vertices are colored the same?
Note: In graph theory, two vertices are adjacent if they share an edge.
by
Andrew Hayes
Are you sure you want to view the solution?
±1±2±3±⋯±2017±2018=?
Using appropriate + and - signs on the left side of the equation, which number can be obtained on the right?
by
Julian Yu
Are you sure you want to view the solution?
Triangle ABC is inscribed in a circle. The angle ABC is obtuse, and the altitude CH is tangent to the circle.
If HB=10 and BA=8, what is the radius of the circle?
by
Jeremy Galvagni
Are you sure you want to view the solution?
Tom was born on a Thursday in either 2014, 2015, 2016, or 2017. What is the oldest age Tom can turn on his next Thursday birthday?
Hint: Consider the remainder when the number of days in a year (365) is divided by the number of days in a week (7). But don't forget about leap years!
by
Stephen Mellor
Are you sure you want to view the solution?