Number Recreations

Shyam Sunder Gupta
Former Principal Chief Engineer,
North Western Railway, Jaipur, India-302017

What is New? (Update 31 December, 2023)

Happy New Year 2024

  • My Book Creative Puzzles to Ignite Your Mind published by SPRINGER was featured in "The Guardian" (UK). Mr. Alex Bellos, in his biweekly puzzle column in the Guardian covered some simple puzzles from my book.
    Can you solve it? The man who made India's trains run on time
    Did you solve it? The man who made India's trains run on time

  • My Paper Amazing Shapes Using Factorial Digits is published in the November 2023 issue of "At Right Angles".

  • The page on Fascinating Triangular Numbers updated.

  • CYF NO. 57 Contribution by Alessandro Casini and M F Hasler given.

  • CYF NO. 58 Contribution by M F Hasler and Shyam Sunder Gupta given.

  • Prime curios 102, 135, 152, 610, 828, 3689, 11956, 39808, 99377, 235541, 256541, 310747, 995957, 999983, 1380563, 4999999, 8640889, 11111117, 27596801, 57595919, 77111777, 93668033, 98579851, 102345689, 402158963, 4832397985356295141, 35137...28561 (24-digits), 11854...00001 (33-digits), 18033...56381 (33-digits), 59265...28841 (34-digits), 71737...31137 (36-digits), 23558...83999 (50-digits), 11187...99999 (72-digits), 12345...15253 (76-digits), 27125...00763 (84-digits), 15156...71519 (100-digits), 10000...43723 (101-digits), 85047...10767 (102-digits), 20162...69453 (300-digits), 16917...12313 (435-digits), 99999...20351 (666-digits), 10000...58749 (666-digits), 62818...14517 (792-digits), 10270...42019 (836-digits), 49894...61393 (988-digits), 35791...17719 (1024-digits), 14001...10041 (1073-digits), 14317...57661 (1404-digits), 17902...20971 (8271-digits) added.

Do You Know?

    The only way to express three fractions containing just the nine digits to have a sum of 1 is 9/12 + 7/68 + 5/34 = 1.

Can You Find?

CYF NO. 59
A palindromic number other than 4607064 that can be expressed as the sum of two cubes in two different ways.

email your answer


Note: The above topics including many more will be added in due course.


My Contributions in Prime Curios

Prime Curios! - site maintained by G. L. Honaker Jr. and Chris Caldwell

My Favorite Links

  • Magic Squares,Magic Stars and Other Interesting number patterns by Harvey Heinz
  • Mudd Math Fun Facts pages
  • On-Line Encyclopedia of Integer Sequences OEIS
  • Math Puzzles
    An interesting site with lot of math recreations by Ed Pegg Jr.

My Favorite Books

Recommended list of books for those interested in Recreational and Computational Number theory
In Association with In Association with

The Rail
(January, 2003)

(March, 2003)
The Busy Educator Award
(October, 2003)

Send me e-mail at

This page was last updated on 31st December, 2023.

Copyright 2023-2024 Shyam Sunder Gupta. All rights reserved.