This is a rather remarkable problem from the 2025 Math Calendar.
“What is the value of
mod33(20252025)
where moda(b) is the remainder r < a after a divides b, that is,
b = ma + r
for some integer m.”
Recall that the answer is a day of the month.
See Modular Arithmetic Puzzle for a solution.
This is a simple problem from the 2026 Math Calendar.
“Find the area of the rectangle.”
Again, the result must be a number of a day in a month.
See Area of Rectangle for solutions.
This is another challenging sum from the 2025 Math Calendar.
“Find x where x = 1/y and
”
As before, recall that all the answers are integer days of the month.
See Spring Sum for a solution.
This is a bit of a challenging problem from the 2026 Math Calendar.
“Let f be a continuous real-valued function on the reals. For all t, f(2t) = 3 f(t) and ∫01 f(t) dt = 1.
What is the value of ∫24 f(t) dt ?”
Again, the result must be a number of a day in a month.
See Integral Challenge for a solution.
Here are two problems involving those pesky radicals from the 2025 Math Calendar.
“#1. Find the value of the expression 
#2. Find the value of x in the expression
Incredibly the answers are days on the calendar.
See Two Radical Problems for solutions.
Here are two algebra problems from the 2025 Math Calendar.
“#1. Find the value of the ratio
#2. Find the value of the sum
z90 + z87 + … + z3 + 1
where z2 + z + 1 = 0.”
Remember the answers are days on the calendar.
See Two Algebra Puzzles for solutions.
This is another typical travel puzzle from the 2024 Math Calendar.
“A boat travels downriver at 30 mph, then goes back up along the same path at 20 mph. What is the boat’s average speed?”
As before, recall that all the answers are integer days of the month.
See Another Boat Puzzle for a solution.
This is a curious relation from the 2024 Math Calendar.
“10! seconds is exactly how many weeks?”
As before, recall that all the answers are integer days of the month, and also recall that 10! = 10x9x8x … x3x2x1.
See a Curious Calendar Puzzle for a solution.
This is another nice problem from the 2025 Math Calendar.
“The two squares in the diagram have areas 9 and 16 and form two of the sides of a triangle with area 3. What is the area x of the blue triangle?”
Again, the result must be a number of a day in a month.
See the Two Squares Puzzle for a solution.
This is another challenging sum from the 2024 Math Calendar.
“Find x where x = et and
”
As before, recall that all the answers are integer days of the month.
See Yet Another Sum for a solution.
