REVERSAL-ADDITION PALINDROME TEST ON 110909992

Reverse and Add Process:

1. Pick a number.
2. Reverse its digits and add this value to the original number.
3. If this is not a palindrome, go back to step 2 and repeat.
Let's view this Reverse and Add sequence starting with 110909992:
110909992
+ 299909011
step 1: 410819003
+ 300918014
step 2: 711737017
+ 710737117
step 3: 1422474134
+ 4314742241
step 4: 5737216375
+ 5736127375
step 5: 11473343750
+ 05734337411
step 6: 17207681161
+ 16118670271
step 7: 33326351432
+ 23415362333
step 8: 56741713765
+ 56731714765
step 9: 113473428530
+ 035824374311
step 10: 149297802841
+ 148208792941
step 11: 297506595782
+ 287595605792
step 12: 585102201574
+ 475102201585
step 13: 1060204403159
+ 9513044020601
step 14: 10573248423760
+ 06732484237501
step 15: 17305732661261
+ 16216623750371
step 16: 33522356411632
+ 23611465322533
step 17: 57133821734165
+ 56143712833175
step 18: 113277534567340
+ 043765435772311
step 19: 157042970339651
+ 156933079240751
step 20: 313976049580402
+ 204085940679313
step 21: 518061990259715
+ 517952099160815
step 22: 1036014089420530
+ 0350249804106301
step 23: 1386263893526831
+ 1386253983626831
step 24: 2772517877153662
+ 2663517787152772
step 25: 5436035664306434
+ 4346034665306345
step 26: 9782070329612779
+ 9772169230702879
step 27: 19554239560315658
+ 85651306593245591
step 28: 105205546153561249
+ 942165351645502501
step 29: 1047370897799063750
+ 0573609977980737401
step 30: 1620980875779801151
+ 1511089775780890261
step 31: 3132070651560691412
+ 2141960651560702313
step 32: 5274031303121393725
+ 5273931213031304725
step 33: 10547962516152698450
+ 05489625161526974501
step 34: 16037587677679672951
+ 15927697677678573061
step 35: 31965285355358246012
+ 21064285355358256913
step 36: 53029570710716502925
+ 52920561701707592035
step 37: 105950132412424094960
+ 069490424214231059501
step 38: 175440556626655154461
+ 164451556626655044571
step 39: 339892113253310199032
+ 230991013352311298933
step 40: 570883126605621497965
+ 569794126506621388075
step 41: 1140677253112242886040
+ 0406882422113527760411
step 42: 1547559675225770646451
+ 1546460775225769557451
step 43: 3094020450451540203902
+ 2093020451540540204903
step 44: 5187040901992080408805
+ 5088040802991090407815
step 45: 10275081704983170816620
+ 02661807138940718057201
step 46: 12936888843923888873821
+ 12837888832934888863921
step 47: 25774777676858777737742
+ 24773777785867677747752
step 48: 50548555462726455485494
+ 49458455462726455584505
step 49: 100007010925452911069999
+ 999960119254529010700001
step 50: 1099967130179981921770000
+ 0000771291899710317699901
step 51: 1100738422079692239469901
+ 1099649322969702248370011
step 52: 2200387745049394487839912
+ 2199387844939405477830022
step 53: 4399775589988799965669934
+ 4399665699978899855779934
step 54: 8799441289967699821449868
+ 8689441289967699821449978
step 55: 17488882579935399642899846
+ 64899824699353997528888471
step 56: 82388707279289397171788317
+ 71388717179398297270788328
step 57: 153777424458687694442576645
+ 546675244496786854424777351
step 58: 700452668955474548867353996
+ 699353768845474559866254007
step 59: 1399806437800949108733608003
+ 3008063378019490087346089931
step 60: 4407869815820439196079697934
+ 4397969706919340285189687044
step 61: 8805839522739779481269384978
+ 8794839621849779372259385088
step 62: 17600679144589558853528770066
+ 66007782535885598544197600671
step 63: 83608461680475157397726370737
+ 73707362779375157408616480638
step 64: 157315824459850314806342851375
+ 573158243608413058954428513751
step 65: 730474068068263373760771365126
+ 621563177067373362860860474037
step 66: 1352037245135636736621631839163
+ 3619381361266376365315427302531
step 67: 4971418606402013101937059141694
+ 4961419507391013102046068141794
step 68: 9932838113793026203983127283488
+ 8843827213893026203973118382399
step 69: 18776665327686052407956245665887
+ 78856654265970425068672356667781
step 70: 97633319593656477476628602333668
+ 86633320682667477465639591333679
step 71: 184266640276323954942268193667347
+ 743766391862249459323672046662481
step 72: 928033032138573414265940240329828
+ 828923042049562414375831230330829
step 73: 1756956074188135828641771470660657
+ 7560660741771468285318814706596571
step 74: 9317616815959604113960586177257228
+ 8227527716850693114069595186167139
step 75: 17545144532810297228030181363424367
+ 76342436318103082279201823544154571
step 76: 93887580850913379507232004907578938
+ 83987570940023270597331905808578839
step 77: 177875151790936650104563910716157777
+ 777751617019365401056639097151578771
step 78: 955626768810302051161203007867736548
+ 845637768700302161150203018867626559
step 79: 1801264537510604212311406026735363107
+ 7013635376206041132124060157354621081
step 80: 8814899913716645344435466184089984188
+ 8814899804816645344435466173199984188
step 81: 17629799718533290688870932357289968376
+ 67386998275323907888609233581799792671
step 82: 85016797993857198577480165939089761047
+ 74016798093956108477589175839979761058
step 83: 159033596087813307055069341779069522105
+ 501225960977143960550703318780695330951
step 84: 660259557064957267605772660559764853056
+ 650358467955066277506762759460755952066
step 85: 1310618025020023545112535420020520805122
+ 2215080250200245352115453200205208160131
step 86: 3525698275220268897227988620225728965253
110909992 takes 86 iterations / steps to resolve into a 40 digit palindrome.

REVERSAL-ADDITION PALINDROME RECORDS

Most Delayed Palindromic Number for each digit length
(Only iteration counts for which no smaller records exist are considered. My program records only the smallest number that resolves for each distinct iteration count. For example, there are 18-digit numbers that resolve in 232 iterations, higher than the 228 iteration record shown for 18-digit numbers, but they were not recorded, as a smaller [17-digit] number already holds the record for 232 iterations.)

DigitsNumberResult
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19 		89
187
1,297
10,911
150,296
9,008,299
10,309,988
140,669,390
1,005,499,526
10,087,799,570
100,001,987,765
1,600,005,969,190
14,104,229,999,995
100,120,849,299,260
1,030,020,097,997,900
10,442,000,392,399,960
170,500,000,303,619,996
1,186,060,307,891,929,990
 solves in 24 iterations.
solves in 23 iterations.
solves in 21 iterations.
solves in 55 iterations.
solves in 64 iterations.
solves in 96 iterations.
solves in 95 iterations.
solves in 98 iterations.
solves in 109 iterations.
solves in 149 iterations.
solves in 143 iterations.
solves in 188 iterations.
solves in 182 iterations.
solves in 201 iterations.
solves in 197 iterations.
solves in 236 iterations.
solves in 228 iterations.
solves in 261 iterations - World Record!
[View all records]

This reverse and add program was created by Jason Doucette.
Please visit my Palindromes and World Records page.
You have permission to use the data from this webpage (with due credit).
A link to my website is much appreciated. Thank you.

(This program has been run 2,550,015 times since Saturday, March 9th, 2002.)