REVERSAL-ADDITION PALINDROME TEST ON 180005498

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 180005498:
180005498
+ 894500081
step 1: 1074505579
+ 9755054701
step 2: 10829560280
+ 08206592801
step 3: 19036153081
+ 18035163091
step 4: 37071316172
+ 27161317073
step 5: 64232633245
+ 54233623246
step 6: 118466256491
+ 194652664811
step 7: 313118921302
+ 203129811313
step 8: 516248732615
+ 516237842615
step 9: 1032486575230
+ 0325756842301
step 10: 1358243417531
+ 1357143428531
step 11: 2715386846062
+ 2606486835172
step 12: 5321873681234
+ 4321863781235
step 13: 9643737462469
+ 9642647373469
step 14: 19286384835938
+ 83953848368291
step 15: 103240233204229
+ 922402332042301
step 16: 1025642565246530
+ 0356425652465201
step 17: 1382068217711731
+ 1371177128602831
step 18: 2753245346314562
+ 2654136435423572
step 19: 5407381781738134
+ 4318371871837045
step 20: 9725753653575179
+ 9715753563575279
step 21: 19441507217150458
+ 85405171270514491
step 22: 104846678487664949
+ 949466784876648401
step 23: 1054313463364313350
+ 0533134633643134501
step 24: 1587448097007447851
+ 1587447007908447851
step 25: 3174895104915895702
+ 2075985194015984713
step 26: 5250880298931880415
+ 5140881398920880525
step 27: 10391761697852760940
+ 04906725879616719301
step 28: 15298487577469480241
+ 14208496477578489251
step 29: 29506984055047969492
+ 29496974055048960592
step 30: 59003958110096930084
+ 48003969001185930095
step 31: 107007927111282860179
+ 971068282111729700701
step 32: 1078076209223012560880
+ 0880652103229026708701
step 33: 1958728312452039269581
+ 1859629302542138278591
step 34: 3818357614994177548172
+ 2718457714994167538183
step 35: 6536815329988345086355
+ 5536805438899235186356
step 36: 12073620768887580272711
+ 11727208578886702637021
step 37: 23800829347774282909732
+ 23790928247774392800832
step 38: 47591757595548675710564
+ 46501757684559575719574
step 39: 94093515280108251430138
+ 83103415280108251539049
step 40: 177196930560216502969187
+ 781969205612065039691771
step 41: 959166136172281542660958
+ 859066245182271631661959
step 42: 1818232381354553174322917
+ 7192234713554531832328181
step 43: 9010467094909085006651098
+ 8901566005809094907640109
step 44: 17912033100718179914291207
+ 70219241997181700133021971
step 45: 88131275097899880047313178
+ 87131374008899879057213188
step 46: 175262649106799759104526366
+ 663625401957997601946262571
step 47: 838888051064797361050788937
+ 739887050163797460150888838
step 48: 1578775101228594821201677775
+ 5777761021284958221015778751
step 49: 7356536122513553042217456526
+ 6256547122403553152216356537
step 50: 13613083244917106194433813063
+ 36031833449160171944238031631
step 51: 49644916694077278138671844694
+ 49644817683187277049661944694
step 52: 99289734377264555188333789388
+ 88398733388155546277343798299
step 53: 187688467765420101465677587687
+ 786785776564101024567764886781
step 54: 974474244329521126033442474468
+ 864474244330621125923442474479
step 55: 1838948488660142251956884948947
+ 7498494886591522410668848498381
step 56: 9337443375251664662625733447328
+ 8237443375262664661525733447339
step 57: 17574886750514329324151466894667
+ 76649866415142392341505768847571
step 58: 94224753165656721665657235742238
+ 83224753275656612765656135742249
step 59: 177449506441313334431313371484487
+ 784484173313134433313144605944771
step 60: 961933679754447767744457977429258
+ 852924779754447767744457976339169
step 61: 1814858459508895535488915953768427
+ 7248673595198845355988059548584181
step 62: 9063532054707740891476975502352608
+ 8062532055796741980477074502353609
step 63: 17126064110504482871954050004706217
+ 71260740005045917828440501146062171
step 64: 88386804115550400700394551150768388
+ 88386705115549300700405551140868388
step 65: 176773509231099701400800102291636776
+ 677636192201008004107990132905377671
step 66: 854409701432107705508790235197014447
+ 744410791532097805507701234107904458
step 67: 1598820492964205511016491469304918905
+ 5098194039641946101155024692940288951
step 68: 6697014532606151612171516162245207856
+ 6587025422616151712161516062354107966
step 69: 13284039955222303324333032224599315822
+ 22851399542223033342330322255993048231
step 70: 36135439497445336666663354480592364053
+ 35046329508445336666663354479493453163
step 71: 71181769005890673333326708960085817216
+ 61271858006980762333337609850096718117
step 72: 132453627012871435666664318810182535333
+ 333535281018813466666534178210726354231
step 73: 465988908031684902333198497020908889564
+ 465988809020794891333209486130809889564
step 74: 931977717052479793666407983151718779128
+ 821977817151389704666397974250717779139
step 75: 1753955534203869498332805957402436558267
+ 7628556342047595082338949683024355593571
step 76: 9382511876251464580671755640426792151838
+ 8381512976240465571760854641526781152839
step 77: 17764024852491930152432610281953573304677
+ 77640337535918201623425103919425842046771
step 78: 95404362388410131775857714201379415351448
+ 84415351497310241775857713101488326340459
step 79: 179819713885720373551715427302867741691907
+ 709196147768203724517155373027588317918971
step 80: 889015861653924098068870800330456059610878
+ 878016950654033008078860890429356168510988
step 81: 1767032812307957106147731690759812228121866
+ 6681218222189570961377416017597032182307671
step 82: 8448251034497528067525147708356844410429537
+ 7359240144486538077415257608257944301528448
step 83: 15807491178984066144940405316614788711957985
+ 58975911788741661350404944166048987119470851
step 84: 74783402967725727495345349482663775831428836
+ 63882413857736628494354359472752776920438747
step 85: 138665816825462355989699708955416552751867583
+ 385768157255614559807996989553264528618566831
step 86: 524433974081076915797696698508681081370434414
+ 414434073180186805896696797519670180479334425
step 87: 938868047261263721694393496028351261849768839
+ 938867948162153820694393496127362162740868839
step 88: 1877735995423417542388786992155713424590637678
+ 8767360954243175512996878832457143245995377781
step 89: 10645096949666593055385665824612856670586015459
+ 95451068507665821642856658355039566694969054601
step 90: 106096165457332414698242324179652423365555070060
+ 060070555563324256971423242896414233754561690601
step 91: 166166721020656671669665567076066657120116760661
+ 166067611021756660670765566966176656020127661661
step 92: 332234332042413332340431134042243313140244422322
+ 223224442041313342240431134043233314240233432233
step 93: 555458774083726674580862268085476627380477854555
180005498 takes 93 iterations / steps to resolve into a 48 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 1,792,336 times since Saturday, March 9th, 2002.)