A ladder has 100 steps. On the first step sits 1 pigeon; on the second, 2; on the third, 3; and so on up to the hundredth. How many pigeons in all?

Individual problems from throughout mathematics history, as well as articles that include problem sets for students.

Show that the curves x2 - y2 = a2 and 2 xy = b2 cross at right angles.

A teacher agreed to teach 9 months for $562.50 and his board. At the end of the term, on account of two months absence caused by sickness, he received only $409.50. What was his board worth per month?

Two men have a certain amount of money. The first says to the second, "If you give me 5 denari, I will have 7 times what you have left."

Find the isoceles triangle of smallest area that circumscribes a circle of radius 1.

If I were to give 7 pennies to each beggar at my door, I would have 24 pennies left in my purse. How many beggars are there and how much money do I have?

In a right triangle, the hypotenuse is 9.434 and the sum of the sides around the right angle is 13. Find the lengths of the sides around the right angle.

A horse halving its speed every day runs 700 miles in 7 days.

Four men already having denari found a purse of denari; each man has a different amount of denari before they found the purse. Find out how much denari each man has.

How a translation of Peano's counterexample to the 'theorem' that a zero Wronskian implies linear dependence can help your differential equations students