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Ponder This

December 2015

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Ponder This Challenge:

Last month, Gene Amdahl, an IBM fellow who was the chief architect of the legendary IBM 360 system, died at age 92.
In memory of his work, this month's challenge focuses on the IBM-360 character set (EBCDIC):
Find a formula to convert the 52 EBCDIC letters into ASCII using no more than 4 operators.
See for the ASCII and EBCDIC character sets.

Supply your answer as a mathematical expression. For example, one can switch from lower-case ASCII to uppercase ASCII (and vice versa) using a single operation: f(x)=x xor 32.

Update (09/12):

  1. You can use any reasonable operation (even trigonometric functions).

Update (13/12):

  1. Use at most 4 operations, not 4 operations types. For example, the function x-floor((x>>4)*7.65-29), which correctly converts the lower case letters, uses five operation (2 subtractions, shift, multiplication, floor).

We will post the names of those who submit a correct, original solution! If you don't want your name posted then please include such a statement in your submission!

We invite visitors to our website to submit an elegant solution. Send your submission to the

If you have any problems you think we might enjoy, please send them in. All replies should be sent to:


Challenge: 01/12/2015 @ 12:00 PM EST
Solution: 01/01/2016 @ 12:00 PM EST
List Updated: 06/01/2016 @ 12:00 PM EST

People who answered correctly:

James Dow Allen (02/12/2015 11:40 AM IDT)
Septimus Stevens (03/12/2015 04:43 AM IDT)
Christian Häggström (03/12/2015 10:09 AM IDT)
Kang Jin Cho (04/12/2015 01:54 PM IDT)
Armin Krauss (08/12/2015 01:16 PM IDT)
Yan-Wu He (08/12/2015 05:31 PM IDT)
Brian Huffman (10/12/2015 06:21 AM IDT)
David Harrison (11/12/2015 02:13 AM IDT)
Robert Gerbicz (11/12/2015 04:45 PM IDT)
Anders Bisbjerg Madsen (15/12/2015 09:18 PM IDT)
Shirish Chinchalkar (17/12/2015 06:59 AM IDT)
David Dunkley (17/12/2015 10:38 AM IDT)
Pataki Gida (19/12/2015 06:21 PM IDT)
Michael Rosola (19/12/2015 09:52 PM IDT)
Harald Bögeholz (20/12/2015 07:42 PM IDT)
Gregory Giecold (21/12/2015 06:40 AM IDT)
Andreas Stiller (23/12/2015 02:50 AM IDT)
Mathias Schenker (26/12/2015 10:52 AM IDT)
Motty Porat (28/12/2015 05:10 PM IDT)
David Greer (01/01/2016 05:25 AM IDT)
Gringo (02/01/2016 08:05 PM IDT)