Nicomachus
One of the most ancient forms of arithmetic puzzle is sometimes referred to as a “boomerang.” At some time, everyone has been asked to “think of a number,” and, after going through some process of private calculation, to state the result, after which the questioner promptly tells you the number you originally thought of. There are hundreds of varieties of this puzzle.
The oldest recorded example appears to be that given in Arithmetica of Nicomachus, who died about the year 120. He tells you to think of any whole number between 1 and 100 and divide it successfully by 3, 5, and 7, telling him the remainder in each case. On receiving this information, he promptly discloses the number you thought of.
Can you discover a simple method of mentally performing this feat? If not, you can see how the ancient mathematician did it by looking at this program.
Nicomachus was written by David Ahl.
As published in Basic Computer Games (1978):
Downloaded from Vintage Basic at http://www.vintage-basic.net/games.html
Porting Notes
(please note any difficulties or challenges in porting here)