Gretel’s Goldfish

When will Hansel and Gretel have the same number of goldfish?

Summing Multiples

Find a pattern in the sum of multiples.

Raised to the 100th

Use patterns to determine the units digit for numbers raised to the 100th power.

Hypatia’s Triumph

Take on the Egyptian Hypatia’s challenge about sums of squares.

Choosing an Elevator

Based on certain criteria, determine which of two elevators reaches the lobby first.

Almost a Square

A square with sides of integral length (i.e., the side lengths are integers) could be made with 25 square units. Make a rectangle with sides of integral length and an area of 24 square units, but construct the rectangle so it comes as close as possible to being a square. What are the dimensions of […]

Arranging Toothpicks

What is the total number of toothpicks used to build a rectangular grid?


Consider the infinite sums of some numbers.

Hot Air Balloon

Determine the height of a hot air balloon over time based on a recursive condition.

Pascal’s Patterns

Identify patterns in a triangular array of numbers.