Number Recreations

Shyam Sunder Gupta
Principal Chief Engineer,
North Western Railway,
Jaipur, India-302017
Telephone: (0141) 2725871(O)

What is New? (Update 17 December, 2017)

A new page on Amazing Number 108 added.

The page on Fascinating Triangular Numbers updated and enlarged.

DO YOU KNOW (25 October, 2006) Comments by Al Zimmermann given.

DO YOU KNOW (30 October, 2016) Comments by Al Zimmermann given.

Prime curios 5, 7, 216, 1333333 and 15423094826093 added.

Do You Know?

270 is the smallest positive integer such that it has divisors ending with every decimal digit i.e. divisors ending in 0,1,2,3,4,5,6,7,8 and 9.

Can You Find?

CYF NO. 49
The smallest Abundant number which is also pseudoprime (base-2).

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 17th December, 2017.

Copyright 2001-2018 Shyam Sunder Gupta. All rights reserved.