REVERSAL-ADDITION PALINDROME TEST ON 1007377 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 1007377: 1007377 + 7737001 step 1: 8744378 + 8734478 step 2: 17478856 + 65887471 step 3: 83366327 + 72366338 step 4: 155732665 + 566237551 step 5: 721970216 + 612079127 step 6: 1334049343 + 3439404331 step 7: 4773453674 + 4763543774 step 8: 9536997448 + 8447996359 step 9: 17984993807 + 70839948971 step 10: 88824942778 + 87724942888 step 11: 176549885666 + 666588945671 step 12: 843138831337 + 733138831348 step 13: 1576277662685 + 5862667726751 step 14: 7438945389436 + 6349835498347 step 15: 13788780887783 + 38778808788731 step 16: 52567589676514 + 41567698576525 step 17: 94135288253039 + 93035288253149 step 18: 187170576506188 + 881605675071781 step 19: 1068776251577969 + 9697751526778601 step 20: 10766527778356570 + 07565387772566701 step 21: 18331915550923271 + 17232905551913381 step 22: 35564821102836652 + 25663820112846553 step 23: 61228641215683205 + 50238651214682216 step 24: 111467292430365421 + 124563034292764111 step 25: 236030326723129532 + 235921327623030632 step 26: 471951654346160164 + 461061643456159174 step 27: 933013297802319338 + 833913208792310339 step 28: 1766926506594629677 + 7769264956056296671 step 29: 9536191462650926348 + 8436290562641916359 step 30: 17972482025292842707 + 70724829252028427971 step 31: 88697311277321270678 + 87607212377211379688 step 32: 176304523654532650366 + 663056235456325403671 step 33: 839360759110858054037 + 730450858011957063938 step 34: 1569811617122815117975 + 5797115182217161189651 step 35: 7366926799339976307626 + 6267036799339976296637 step 36: 13633963598679952604263 + 36240625997689536933631 step 37: 49874589596369489537894 + 49873598496369598547894 step 38: 99748188092739088085788 + 88758088093729088184799 step 39: 188506276186468176270587 + 785072671864681672605881 step 40: 973578948051149848876468 + 864678848941150849875379 step 41: 1838257796992300698751847 + 7481578960032996977528381 step 42: 9319836757025297676280228 + 8220826767925207576389139 step 43: 17540663524950505252669367 + 76396625250505942536604571 step 44: 93937288775456447789273938 + 83937298774465457788273939 step 45: 177874587549921905577547877 + 778745775509129945785478771 step 46: 956620363059051851363026648 + 846620363158150950363026659 step 47: 1803240726217202801726053307 + 7033506271082027126270423081 step 48: 8836746997299229927996476388 1007377 takes 48 iterations / steps to resolve into a 28 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.) Digits Number Result 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 2,549,991 times since Saturday, March 9th, 2002.)