Number Recreations

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

What is New? (Update 11 November, 2021)

The page on Curious Properties of 153 updated.

The page on Fascinating Triangular Numbers updated.

CYF NO. 52 and 54 Comments by late shri K D Bajpai given.

CYF NO. 54 Comments by Shyam Sunder Gupta given.

CYF NO. 7 and 9 Comments by Mauro Fiorentini given.

Do You Know?

The number of letters in the thirteen cards of a suit i.e. ACE, TWO, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT, NINE, TEN, JACK, QUEEN and KING is 52 which is the number of cards in the standard deck of playing cards.

Can You Find?

CYF NO. 55
The largest number (or as large as you can) n such that both n and nth triangular numbers consists of odd digits only.

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 11th November, 2021.

Copyright 2001-2021 Shyam Sunder Gupta. All rights reserved.