REVERSAL-ADDITION PALINDROME TEST ON 10029372

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 10029372:
10029372
+ 27392001
step 1: 37421373
+ 37312473
step 2: 74733846
+ 64833747
step 3: 139567593
+ 395765931
step 4: 535333524
+ 425333535
step 5: 960667059
+ 950766069
step 6: 1911433128
+ 8213341191
step 7: 10124774319
+ 91347742101
step 8: 101472516420
+ 024615274101
step 9: 126087790521
+ 125097780621
step 10: 251185571142
+ 241175581152
step 11: 492361152294
+ 492251163294
step 12: 984612315588
+ 885513216489
step 13: 1870125532077
+ 7702355210781
step 14: 9572480742858
+ 8582470842759
step 15: 18154951585617
+ 71658515945181
step 16: 89813467530798
+ 89703576431898
step 17: 179517043962696
+ 696269340715971
step 18: 875786384678667
+ 766876483687578
step 19: 1642662868366245
+ 5426638682662461
step 20: 7069301551028706
+ 6078201551039607
step 21: 13147503102068313
+ 31386020130574131
step 22: 44533523232642444
+ 44424623232533544
step 23: 88958146465175988
+ 88957156464185988
step 24: 177915302929361976
+ 679163929203519771
step 25: 857079232132881747
+ 747188231232970758
step 26: 1604267463365852505
+ 5052585633647624061
step 27: 6656853097013476566
+ 6656743107903586566
step 28: 13313596204917063132
+ 23136071940269531331
step 29: 36449668145186594463
+ 36449568154186694463
step 30: 72899236299373288926
+ 62988237399263299827
step 31: 135887473698636588753
+ 357885636896374788531
step 32: 493773110595011377284
+ 482773110595011377394
step 33: 976546221190022754678
+ 876457220091122645679
step 34: 1853003441281145400357
+ 7530045411821443003581
step 35: 9383048853102588403938
+ 8393048852013588403839
step 36: 17776097705116176807777
+ 77770867161150779067771
step 37: 95546964866266955875548
+ 84557855966266846964559
step 38: 180104820832533802840107
+ 701048208335238028401081
step 39: 881153029167771831241188
+ 881142138177761920351188
step 40: 1762295167345533751592376
+ 6732951573355437615922671
step 41: 8495246740700971367515047
+ 7405157631790070476425948
step 42: 15900404372491041843940995
+ 59904934814019427340400951
step 43: 75805339186510469184341946
+ 64914348196401568193350857
step 44: 140719687382912037377692803
+ 308296773730219283786917041
step 45: 449016461113131321164609844
+ 448906461123131311164610944
step 46: 897922922236262632329220788
+ 887022923236262632229229798
step 47: 1784945845472525264558450586
+ 6850548554625252745485494871
step 48: 8635494400097778010043945457
+ 7545493400108777900044945368
step 49: 16180987800206555910088890825
+ 52809888001955560200878908161
step 50: 68990875802162116110967798986
+ 68989776901161126120857809986
step 51: 137980652703323242231825608972
+ 279806528132242323307256089731
step 52: 417787180835565565539081698703
+ 307896180935565565538081787714
step 53: 725683361771131131077163486417
+ 714684361770131131177163386527
step 54: 1440367723541262262254326872944
+ 4492786234522622621453277630441
step 55: 5933153958063884883707604503385
+ 5833054067073884883608593513395
step 56: 11766208025137769767316198016780
+ 08761089161376796773152080266711
step 57: 20527297186514566540468278283491
+ 19438287286404566541568179272502
step 58: 39965584472919133082036457555993
+ 39955575463028033191927448556993
step 59: 79921159935947166273963906112986
+ 68921160936937266174953995112997
step 60: 148842320872884432448917901225983
+ 389522109719844234488278023248841
step 61: 538364430592728666937195924474824
+ 428474429591739666827295034463835
step 62: 966838860184468333764490958938659
+ 956839859094467333864481068838669
step 63: 1923678719278935667628972027777328
+ 8237777202798267665398729178763291
step 64: 10161455922077203333027701206540619
+ 91604560210772033330277022955416101
step 65: 101766016132849236663304724161956720
+ 027659161427403366632948231610667101
step 66: 129425177560252603296252955772623821
+ 128326277559252692306252065771524921
step 67: 257751455119505295602505021544148742
+ 247841445120505206592505911554157752
step 68: 505592900240010502195010933098306494
+ 494603890339010591205010042009295505
step 69: 1000196790579021093400020975107601999
+ 9991067015790200043901209750976910001
step 70: 10991263806369221137301230726084512000
+ 00021548062703210373112296360836219901
step 71: 11012811869072431510413527086920731901
+ 10913702968072531401513427096811821011
step 72: 21926514837144962911926954183732552912
+ 21925523738145962911926944173841562912
step 73: 43852038575290925823853898357574115824
+ 42851147575389835832852909257583025834
step 74: 86703186150680761656706807615157141658
+ 85614175151670860765616708605168130768
step 75: 172317361302351622422323516220325272426
+ 624272523022615323224226153203163713271
step 76: 796589884324966945646549669423488985697
10029372 takes 76 iterations / steps to resolve into a 39 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 1,717,150 times since Saturday, March 9th, 2002.)