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.

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After completing this assignment on Simon Stevin's treatment of decimal fractions in his 1585 De Thiende, the author's preservice mathematics teachers understood why our usual procedure for multiplying such fractions works.

There are two piles, one containing 9 gold coins, the other 11 silver coins.

A collection of short lectures by Howard Eves giving details on 20 important happenings in the history of mathematics before 1650.

Having been given the lengths, a and b, of two straight lines drawn from the acute angles of a right triangle to the middle of the opposite sides, determine the lengths of those sides.

In the middle of the 18th century, King Frederick the Great of Prussia became interested in creating a lottery to raise money. As was his custom when mathematical matters were involved, he called upon Leonhard Euler for counsel.

Explain the geometric basis of "completing the square," the original method of solving quadratic equations, to your students.

There are two numbers whose sum equals the difference of their squares.

The movie Agora, about the mathematician Hypatia of Alexandria (c. 400 AD), is spectacular and intriguing but Hypatia should be portrayed as the hero she was.

A biography of Arthur Cayley, the outstanding mathematician of Victorian Britain.