What Is New |
28 April, 2024:
A new 32114-digit, easy-to-remember prime reported by me on the Number Theory Mailing List on March 7, 2024 was featured in the Dutch national daily newspaper NRC on Saturday, April 13, 2024, by Alex van den Brandhof (a science journalist).
The page on Happy Numbers added.
The page on Fascinating Triangular Numbers updated.
CYF NO. 59 Contribution by Al Zimmermann, Giorgos Kalogeropoulos and Alessandro Casini given.
Prime curios 7, 97, 131, 270, 491, 631, 882, 1621, 2477, 62745, 546289, 245044800, 47167...14213 (28-digits), 23456...89123 (32114-digits). added.
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”.
31 December, 2023:
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.
12 July, 2023:
The page on Fascinating Triangular Numbers updated.
My New Book Creative Puzzles to Ignite Your Mind has been published by SPRINGER, one of the largest international publisher of academic books.
The book is for puzzle enthusiasts and math lovers, in addition to aspirants of the Math Olympiad, CAT/MBA, and job interviews of big companies like Google, Microsoft, Amazon, Apple, etc.
CYF NO. 49 Comments by Daniel Suteu given.
CYF NO. 57 Solution by Alessandro Casini, M F Hasler, Brian Trial, and Richard Gosiorovsky given.
12 September, 2022:
The page on Vampire Numbers added.
The page on Fascinating Triangular Numbers updated.
CYF NO. 49 Comments by Daniel Suteu given.
CYF NO. 56 Solution by Alessandro Casini given.
CYF NO. 55 Contribution by Al Zimmermann and Maximilian given.
14 March, 2022:
The page on The Number of the Beast 666 added.
The page on Fascinating Triangular Numbers updated.
CYF NO. 55 Contribution by Al Zimmermann, Maximilian and Giorgos Kalogeropoulos given.
Prime curios 17, 25, 94, 111, 587, 1111, 3527, 11956, 122265, 314159, 912673, 962963, 5261941, 5794777, 4592307816, 7775737169, 97959391, 9876541023, 9876542103, 141592653589, 41434547495153, 3637383940414243, 4936251694114916253649, 34149...97531 (39-digits), 72951...12729 (41-digits), 46260...12101(56-digits), 78583...21291 (70-digits), 36132...24361(90-digits), 57137...97531 (209-digits), 12491...11753 (216-digits), 14159...07021 (547-digits), 42574...61941 (948-digits), 76937...11753 (1998-digits), 21309...67281 (5062-digits) and 72180...10631 (6560-digits) added.
Integer Sequences A350755, A350368, A350367, A349696, A350304, A350303, A349773, A349722, A349774, A349539 added.
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.
12 April, 2021:
The page on Amicable Numbers updated.
The page on Fascinating Triangular Numbers updated.
The page on Unlucky 13 updated.
CYF NO. 53 Solution by Al Zimmermann and Brian Trial given.
CYF NO. 49 Comments by Daniel Suteu given.
Prime curios 62,102,181,199,293,373,881,993, 1524,1609,3527,6031,6691,7740,7757,9257,9647 and many more added.
17 June, 2020:
The page on Rare Numbers updated (including list up to 10^{23}).
Prime curios 11, 1427, 44936, 120689, 132882, 480585, 206913578, 511733945 and many more added.
14 December, 2019:
The page on Rare Numbers updated (including list up to 10^{22}).
CYF NO. 49 Comments by Daniel Suteu given.
CYF NO. 51 Comments by Jens Kruse Andersen given.
Prime curios 12, 182, 10342, 49141, 10234567 and many more added.
15 September, 2019:
The page on Fascinating Triangular Numbers updated and enlarged.
The page on Rare Numbers updated.
CYF NO. 50 Solution by Al Zimmermann, Brian Trial, Emmanuel Vantieghem and Alessandro Casini given.
Prime curios
11,13,19,31,107,127,199,373,712,797,919,929,1213,1217,1229,1279,1586,3169,3257,4514,5701,7613,7739,11047,15841,16561,21023,35731,38069,46099,100049,
105683,176861,494639,670033,1015423,1059443,1148527,1324913,1460189,1530787,2012101,5133127,10152463,57486888,941056273,987654301,1012356487,1041293663,
1123456798,1123548967,1223574689,2459868287, 43167...36781(34-digits),15171...11113(107-digits),46445...32211(129-digits), 28799...94029(530-digits), 59999...99999 (14564-digits) and many more
added.
28 November, 2018:
The page on Amazing Number 108 updated and enlarged.
The page on Fascinating Triangular Numbers updated and enlarged.
The page on Curious Properties of 153 updated and enlarged.
The page on Amicable Numbers updated.
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.
30 October, 2016:
CYF NO. 47 Solution by Bernard Fischel and Brian Trial given.
CYF NO. 47 Comments by Selvam Chidambaram given.
CYF NO. 41 Comments by K D Bajpai given.
Prime curios 5, 853, 13579, 35333, 49019, 95063, 630745, 630745, 1110181, 1120573, 1180811, 1230127, 1440689, 2275327,2770513, 9040861, 14001019, 66410849, 101838101, 188303881, 396808693, 665067264, 968606869, 1023567948, 1124396857, 1124638579, 1124685973, 2547863419, 6650672647, 10123456897, 10123465789, 10124389567, 10125984763, 23457987601, 581321345589144233, 10591...10631(26 digit), 98761...13853(28 digit), 13171...17379 (34 digit), 17101...80291 (108 digit), 11111...11111 (109297 digit) and 11111...11111 (270343 digit) added.
4 November, 2015:
The page on Fascinating Triangular Numbers updated and enlarged.
CYF NO. 46 results by Al Zimmermann and Brian Trial given.
CYF NO. 41 results by Brian Trial and Shyam Sunder Gupta given.
7 July, 2015:
The page on Fascinating Triangular Numbers updated and enlarged.
The page on Curious Properties of 153 updated.
The page on Unique Numbers updated.
CYF NO. 43 solution by Al Zimmermann given
CYF NO. 26 Comments by Mauro Fiorentini given.
CYF NO. 15 Comments by Mauro Fiorentini given.
CYF NO. 7 Comments by Mauro Fiorentini given.
6 October, 2014:
A new page on Fascinating Factorials added.
CYF NO. 11 solution by David Harrison for a difficult and highly computational problem given.
CYF NO. 44 solution by Fred Schneider given.
CYF NO. 31 Comments by Paul Cleary given.
25 December, 2013:
The page on Curious Properties of 153 updated.
CYF NO. 38 Comments by Bernard Fischel given.
Prime curios 13, 4369, 10301, 15709, 75353, 91019, 123191, 303593, 442619, 1120211, 336737123, 904719030, 1123564987, 13201010231, 16831813861, 1123529253211, 3842148274728412483, 3868168229228618683, 164471141292141174461 and 14422...32163 (24-digits) added.
15 July, 2013:
The page on Fascinating Triangular Numbers enlarged.
CYF NO. 42 Comments by Shyam Sunder Gupta given.
CYF NO. 29 Comments by K D Bajpai given.
CYF NO. 21 Solution by K D Bajpai, and Shyam Sunder Gupta given.
Prime curios 311299, 353393243 and 49000...16941 (3742-digits) added.
13 November, 2012:
The page on Unlucky 13 updated and enlarged.
The page on Fascinating Triangular Numbers updated and enlarged.
The page on Curious Properties of 153 updated.
CYF NO. 40 contributions by Carlos Rivera, Maximilian Hasler, Brian Trial given.
CYF NO. 29 Comments by - Mukesh Kr Jha given.
CYF NO. 11 update by David Harrison given.
6 February, 2011:
The page on Curious Properties of 153 updated.
CYF NO. 40 contributions by B.S.Rangaswamy, Bo Gyu Jeong, Norman Luhn, Shyam Sunder Gupta given.
CYF NO. 11 Comments by David Harrison given.
Prime curios 19,101,449,12721,19891,12357321 and many others added.
Integer Sequences A173542,A173543,A173544,A173545 added.
26 January, 2010:
Prime curios 61,67,168,173,227,349,353,378,431,434,701,729,948,1049,1471,1901,36563,60889 and many more added.
10 May, 2009:
The page on Rare Numbers updated and enlarged. (List up to 10^{20 })
Prime curios 2311 and 23111...07673 (33-digits) added.
18 January, 2009:
The page on Smith Numbers updated.
CYF NO. 37 solutions by Luke Pebody , Jens Kruse Andersen, Donovan Johnson, Frederick Schneider given.
CYF NO. 32 Comments by Luke Pebody given.
Prime curios 313 and 95861...78973 (39-digits) added.
30 December, 2007:
Integer Sequences
A131306,A131316,A131535-A131552,A131604-A131606,A131609,
A131612-A131618,A131620,A131625,A131627-A131630
added.
CYF NO. 36 Solution by Luke Pebody, Bruno Mishutka given
14 July, 2007:
Prime curios 4,17,1687,3283,91596...16721 (52-digits),23456...56789 (62-digits),78912...67891 (355-digits),79778...87797 (776-digits),12345...67891 (4690-digits),23456...89123 (4772-digits) added.
CYF NO. 35 Solution by Jaroslaw Wroblewski, Frederick Schneider, Donovan Johnson given
26 January, 2007:
The page on Cab Numbers added.
CYF NO. 34 comments by Brian Trial, Nathan Gilbert given.
25 October, 2006:
The page on Amicable Numbers updated.
CYF NO. 33 solutions by Jens Kruse Andersen, Donovan Johnson, Carlos Rivera, Jacques Bernard, Nathan Gilbert, Gaurav Singh given.
Prime curios 36,1135279341568,1311753223571113,17131175322357111317 added.
15 January, 2006:
Prime curios 1267834459,5748693121,6913548721,12539670481,13069482857,17392546081 added.
CYF NO. 32 Solution by Donovan Johnson given
7 November, 2005:
The page on Amicable Numbers updated.
CYF NO. 31 solutions by B.S.Rangaswamy, Brian Trial, Patrick De Geest given.
Prime curios 23,41,191,1259,1291,22193,102251,3511973,4137473,5521819,5919931, 36101521,210231253,354963229,1914032047,171190210231, 19531891183017701711,18769...17689 (25-digits), 24649...25921 (25-digits) added.
1 May, 2005:
The page on Smith Numbers updated.
CYF NO. 30 comments by Norman Luhn given.
Prime curios 827,6427,15131197,23252729,59575553,2527293133 and 2744337540964913 added.
11 March, 2005:
New page on Smith Numbers added.
1 January, 2005:
Prime curios
41,211,941,6481,235813,292319,59534743,3731292319,4916253649,576529484441,29313741434753,
73727170696867,144121100816449,4847464544434241 and 841784729676625576529
added.
CYF NO. 28 Solution by Jens Kruse Andersen and Donovan Johnson given.
CYF NO. 21 Solution by Donovan Johnson
15 September, 2004:
Prime curios 1,2,3,13,34,56,1801,5779 and many more added.
CYF NO. 27 Solution by Carlos Rivera and Jens Kruse Andersen given.
CYF NO. 1 Comments by Jens Kruse Andersen.
4 May, 2004:
2 March, 2004:
CYF NO. 25 Solution by Jens Kruse Andersen (email dt 04-02-2004) and contributions by Serge Varjabedian and Patrick De Geest given.
1 February, 2004:
CYF NO. 24 Solution by Jens Kruse Andersen (email dt 02-01-2004) and Brian Trial (email dt 12-01-2004) given. Comments added.
1 January, 2004:
8 November, 2003:
3 August, 2003:
13 June, 2003:
21 May, 2003:
29 March, 2003:
1 March, 2003:
1 February, 2003:
1 January, 2003:
1 December, 2002:
11 November, 2002:
New page on My Favorite Books added.
26 October, 2002:
A new page on Fascinating Triangular Numbers added.
5 October, 2002:
CYF NO.12 Results by Jens Kruse Andersen (email dt 25-09-2002)
21 September, 2002:
CYF NO.11 Results by Jens Kruse Andersen (email dt 18-09-2002)
6 September, 2002:
CYF NO.1 Results by Gerbicz Robert (email dt 08-07-2002)
A new page on Smarandache Sequence of Happy Numbers added.
Many Prime Curios added. For details see Prime Curios!
14 April, 2002:
10 March, 2002:
17 February, 2002:
10 February, 2002:
20 January, 2002:
6 January, 2002:
31 December, 2001:
25 December, 2001:
23 December, 2001:
17 December, 2001:
9 December, 2001:
30 November, 2001:
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