REVERSAL-ADDITION PALINDROME TEST ON 989 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 989: 989 + 989 step 1: 1978 + 8791 step 2: 10769 + 96701 step 3: 107470 + 074701 step 4: 182171 + 171281 step 5: 353452 + 254353 step 6: 607805 + 508706 step 7: 1116511 + 1156111 step 8: 2272622 + 2262722 step 9: 4535344 + 4435354 step 10: 8970698 + 8960798 step 11: 17931496 + 69413971 step 12: 87345467 + 76454378 step 13: 163799845 + 548997361 step 14: 712797206 + 602797217 step 15: 1315594423 + 3244955131 step 16: 4560549554 + 4559450654 step 17: 9120000208 + 8020000219 step 18: 17140000427 + 72400004171 step 19: 89540004598 989 takes 19 iterations / steps to resolve into a 11 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 2,542,353 times since Saturday, March 9th, 2002.)