# Problems from Another Time

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

How a translation of Peano's counterexample to the 'theorem' that a zero Wronskian implies linear dependence can help your differential equations students
Rabbits and pheasants are put in a basket.
Now a good horse and an inferior horse set out from Chang'an to Qi. Qi is 3000 li from Chang'an.
Fibonacci gave a practical rule for approximating the area of an equilateral triangle.
Discussion of 15th century French manuscript, with translation of its problems, including one with negative solutions
There is a four-sided field whose eastern side measures 35 paces, its western side 45 paces, its southern side 25 paces and its northern side 15 paces. Find the area of this field.
A lady has two silver cups, and only one cover for both. The first cup weighs 16 oz, and when it is covered it weighs 3 times as much as the second cup; but when the second cup is covered, it weighs 4 times as much as the first.
Now there are six-headed four-legged animals and four-headed two-legged birds. Find the total number of animals and birds.
The sum of the two digits of a 2-digit number is 9. If 45 is subtracted from the number, the result will be expressed by the digits in reverse order. Find the number.
What is the sum of the reciprocals of the triangular numbers?