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 Square - both ways (Posted on 2018-07-28)
What is the smallest number (over 10) that becomes square if its reverse is added or subtracted to it?

Optional: list additional numbers with the above feature.

 No Solution Yet Submitted by Ady TZIDON No Rating

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 computer solutions | Comment 2 of 3 |
The list below starts with the trivial single-digit numbers, whose "reverse" is just the number itself.

Then comes 10, whose reverse is 01, or just 1, which when subtracted is the square number 9.

The first that's neither trivial nor involves a leading zero is 21 - 12 = 9, so this is the smallest.

An interesting feature of the list is that the section dealing with 4-digit numbers has only subtractions--no additions. This is not a general feature of numbers with an even number of digits, as there are some 6-digit numbers in a continuation of this list that work with addition (such as 100895 + 598001 = 698896 = 836^2), though more work with subtraction (such as 102101 - 101201 = 900 = 30^2).  The prevalence of subtraction seems to result from the higher density of perfect squares among lower numbers.

2 + 2 = 4 = 2^2
8 + 8 = 16 = 4^2
10 - 1 = 9 = 3^2
21 - 12 = 9 = 3^2
29 + 92 = 121 = 11^2
32 - 23 = 9 = 3^2
38 + 83 = 121 = 11^2
40 - 4 = 36 = 6^2
43 - 34 = 9 = 3^2
47 + 74 = 121 = 11^2
51 - 15 = 36 = 6^2
54 - 45 = 9 = 3^2
56 + 65 = 121 = 11^2
62 - 26 = 36 = 6^2
65 + 56 = 121 = 11^2
65 - 56 = 9 = 3^2
73 - 37 = 36 = 6^2
74 + 47 = 121 = 11^2
76 - 67 = 9 = 3^2
83 + 38 = 121 = 11^2
84 - 48 = 36 = 6^2
87 - 78 = 9 = 3^2
90 - 9 = 81 = 9^2
92 + 29 = 121 = 11^2
95 - 59 = 36 = 6^2
98 - 89 = 9 = 3^2
110 + 11 = 121 = 11^2
143 + 341 = 484 = 22^2
164 + 461 = 625 = 25^2
198 + 891 = 1089 = 33^2
242 + 242 = 484 = 22^2
263 + 362 = 625 = 25^2
297 + 792 = 1089 = 33^2
341 + 143 = 484 = 22^2
362 + 263 = 625 = 25^2
396 + 693 = 1089 = 33^2
440 + 44 = 484 = 22^2
461 + 164 = 625 = 25^2
495 + 594 = 1089 = 33^2
560 + 65 = 625 = 25^2
594 + 495 = 1089 = 33^2
693 + 396 = 1089 = 33^2
792 + 297 = 1089 = 33^2
891 + 198 = 1089 = 33^2
990 + 99 = 1089 = 33^2
1030 - 301 = 729 = 27^2
1100 - 11 = 1089 = 33^2
1140 - 411 = 729 = 27^2
1210 - 121 = 1089 = 33^2
1250 - 521 = 729 = 27^2
1320 - 231 = 1089 = 33^2
1360 - 631 = 729 = 27^2
1430 - 341 = 1089 = 33^2
1470 - 741 = 729 = 27^2
1540 - 451 = 1089 = 33^2
1580 - 851 = 729 = 27^2
1650 - 561 = 1089 = 33^2
1690 - 961 = 729 = 27^2
1760 - 671 = 1089 = 33^2
1870 - 781 = 1089 = 33^2
1980 - 891 = 1089 = 33^2
2031 - 1302 = 729 = 27^2
2101 - 1012 = 1089 = 33^2
2141 - 1412 = 729 = 27^2
2211 - 1122 = 1089 = 33^2
2251 - 1522 = 729 = 27^2
2321 - 1232 = 1089 = 33^2
2361 - 1632 = 729 = 27^2
2431 - 1342 = 1089 = 33^2
2471 - 1742 = 729 = 27^2
2541 - 1452 = 1089 = 33^2
2581 - 1852 = 729 = 27^2
2651 - 1562 = 1089 = 33^2
2691 - 1962 = 729 = 27^2
2761 - 1672 = 1089 = 33^2
2871 - 1782 = 1089 = 33^2
2981 - 1892 = 1089 = 33^2
3032 - 2303 = 729 = 27^2
3102 - 2013 = 1089 = 33^2
3142 - 2413 = 729 = 27^2
3212 - 2123 = 1089 = 33^2
3252 - 2523 = 729 = 27^2
3322 - 2233 = 1089 = 33^2
3362 - 2633 = 729 = 27^2
3432 - 2343 = 1089 = 33^2
3472 - 2743 = 729 = 27^2
3542 - 2453 = 1089 = 33^2
3582 - 2853 = 729 = 27^2
3652 - 2563 = 1089 = 33^2
3692 - 2963 = 729 = 27^2
3762 - 2673 = 1089 = 33^2
3872 - 2783 = 1089 = 33^2
3982 - 2893 = 1089 = 33^2
4033 - 3304 = 729 = 27^2
4103 - 3014 = 1089 = 33^2
4143 - 3414 = 729 = 27^2
4213 - 3124 = 1089 = 33^2
4253 - 3524 = 729 = 27^2
4323 - 3234 = 1089 = 33^2
4363 - 3634 = 729 = 27^2
4400 - 44 = 4356 = 66^2
4433 - 3344 = 1089 = 33^2
4473 - 3744 = 729 = 27^2
4510 - 154 = 4356 = 66^2
4543 - 3454 = 1089 = 33^2
4583 - 3854 = 729 = 27^2
4620 - 264 = 4356 = 66^2
4653 - 3564 = 1089 = 33^2
4693 - 3964 = 729 = 27^2
4730 - 374 = 4356 = 66^2
4763 - 3674 = 1089 = 33^2
4840 - 484 = 4356 = 66^2
4873 - 3784 = 1089 = 33^2
4950 - 594 = 4356 = 66^2
4983 - 3894 = 1089 = 33^2
5034 - 4305 = 729 = 27^2
5104 - 4015 = 1089 = 33^2
5144 - 4415 = 729 = 27^2
5214 - 4125 = 1089 = 33^2
5254 - 4525 = 729 = 27^2
5324 - 4235 = 1089 = 33^2
5364 - 4635 = 729 = 27^2
5401 - 1045 = 4356 = 66^2
5434 - 4345 = 1089 = 33^2
5474 - 4745 = 729 = 27^2
5511 - 1155 = 4356 = 66^2
5544 - 4455 = 1089 = 33^2
5584 - 4855 = 729 = 27^2
5621 - 1265 = 4356 = 66^2
5654 - 4565 = 1089 = 33^2
5694 - 4965 = 729 = 27^2
5700 - 75 = 5625 = 75^2
5731 - 1375 = 4356 = 66^2
5764 - 4675 = 1089 = 33^2
5810 - 185 = 5625 = 75^2
5841 - 1485 = 4356 = 66^2
5874 - 4785 = 1089 = 33^2
5920 - 295 = 5625 = 75^2
5951 - 1595 = 4356 = 66^2
5984 - 4895 = 1089 = 33^2
6035 - 5306 = 729 = 27^2
6090 - 906 = 5184 = 72^2
6100 - 16 = 6084 = 78^2
6105 - 5016 = 1089 = 33^2
6145 - 5416 = 729 = 27^2
6210 - 126 = 6084 = 78^2
6215 - 5126 = 1089 = 33^2
6255 - 5526 = 729 = 27^2
6320 - 236 = 6084 = 78^2
6325 - 5236 = 1089 = 33^2
6365 - 5636 = 729 = 27^2
6402 - 2046 = 4356 = 66^2
6430 - 346 = 6084 = 78^2
6435 - 5346 = 1089 = 33^2
6475 - 5746 = 729 = 27^2
6512 - 2156 = 4356 = 66^2
6540 - 456 = 6084 = 78^2
6545 - 5456 = 1089 = 33^2
6585 - 5856 = 729 = 27^2
6622 - 2266 = 4356 = 66^2
6650 - 566 = 6084 = 78^2
6655 - 5566 = 1089 = 33^2
6695 - 5966 = 729 = 27^2
6701 - 1076 = 5625 = 75^2
6732 - 2376 = 4356 = 66^2
6760 - 676 = 6084 = 78^2
6765 - 5676 = 1089 = 33^2
6811 - 1186 = 5625 = 75^2
6842 - 2486 = 4356 = 66^2
6870 - 786 = 6084 = 78^2
6875 - 5786 = 1089 = 33^2
6921 - 1296 = 5625 = 75^2
6952 - 2596 = 4356 = 66^2
6980 - 896 = 6084 = 78^2
6985 - 5896 = 1089 = 33^2
7036 - 6307 = 729 = 27^2
7091 - 1907 = 5184 = 72^2
7101 - 1017 = 6084 = 78^2
7106 - 6017 = 1089 = 33^2
7146 - 6417 = 729 = 27^2
7211 - 1127 = 6084 = 78^2
7216 - 6127 = 1089 = 33^2
7256 - 6527 = 729 = 27^2
7321 - 1237 = 6084 = 78^2
7326 - 6237 = 1089 = 33^2
7366 - 6637 = 729 = 27^2
7403 - 3047 = 4356 = 66^2
7431 - 1347 = 6084 = 78^2
7436 - 6347 = 1089 = 33^2
7476 - 6747 = 729 = 27^2
7513 - 3157 = 4356 = 66^2
7541 - 1457 = 6084 = 78^2
7546 - 6457 = 1089 = 33^2
7586 - 6857 = 729 = 27^2
7623 - 3267 = 4356 = 66^2
7651 - 1567 = 6084 = 78^2
7656 - 6567 = 1089 = 33^2
7696 - 6967 = 729 = 27^2
7702 - 2077 = 5625 = 75^2
7733 - 3377 = 4356 = 66^2
7761 - 1677 = 6084 = 78^2
7766 - 6677 = 1089 = 33^2
7812 - 2187 = 5625 = 75^2
7843 - 3487 = 4356 = 66^2
7871 - 1787 = 6084 = 78^2
7876 - 6787 = 1089 = 33^2
7922 - 2297 = 5625 = 75^2
7953 - 3597 = 4356 = 66^2
7981 - 1897 = 6084 = 78^2
7986 - 6897 = 1089 = 33^2
8037 - 7308 = 729 = 27^2
8092 - 2908 = 5184 = 72^2
8102 - 2018 = 6084 = 78^2
8107 - 7018 = 1089 = 33^2
8147 - 7418 = 729 = 27^2
8212 - 2128 = 6084 = 78^2
8217 - 7128 = 1089 = 33^2
8257 - 7528 = 729 = 27^2
8322 - 2238 = 6084 = 78^2
8327 - 7238 = 1089 = 33^2
8367 - 7638 = 729 = 27^2
8404 - 4048 = 4356 = 66^2
8432 - 2348 = 6084 = 78^2
8437 - 7348 = 1089 = 33^2
8477 - 7748 = 729 = 27^2
8514 - 4158 = 4356 = 66^2
8542 - 2458 = 6084 = 78^2
8547 - 7458 = 1089 = 33^2
8587 - 7858 = 729 = 27^2
8624 - 4268 = 4356 = 66^2
8652 - 2568 = 6084 = 78^2
8657 - 7568 = 1089 = 33^2
8697 - 7968 = 729 = 27^2
8703 - 3078 = 5625 = 75^2
8734 - 4378 = 4356 = 66^2
8762 - 2678 = 6084 = 78^2
8767 - 7678 = 1089 = 33^2
8813 - 3188 = 5625 = 75^2
8844 - 4488 = 4356 = 66^2
8872 - 2788 = 6084 = 78^2
8877 - 7788 = 1089 = 33^2
8923 - 3298 = 5625 = 75^2
8954 - 4598 = 4356 = 66^2
8982 - 2898 = 6084 = 78^2
8987 - 7898 = 1089 = 33^2
9038 - 8309 = 729 = 27^2
9093 - 3909 = 5184 = 72^2
9103 - 3019 = 6084 = 78^2
9108 - 8019 = 1089 = 33^2
9148 - 8419 = 729 = 27^2
9213 - 3129 = 6084 = 78^2
9218 - 8129 = 1089 = 33^2
9258 - 8529 = 729 = 27^2
9323 - 3239 = 6084 = 78^2
9328 - 8239 = 1089 = 33^2
9368 - 8639 = 729 = 27^2
9405 - 5049 = 4356 = 66^2
9433 - 3349 = 6084 = 78^2
9438 - 8349 = 1089 = 33^2
9478 - 8749 = 729 = 27^2
9515 - 5159 = 4356 = 66^2
9543 - 3459 = 6084 = 78^2
9548 - 8459 = 1089 = 33^2
9588 - 8859 = 729 = 27^2
9625 - 5269 = 4356 = 66^2
9653 - 3569 = 6084 = 78^2
9658 - 8569 = 1089 = 33^2
9698 - 8969 = 729 = 27^2
9704 - 4079 = 5625 = 75^2
9735 - 5379 = 4356 = 66^2
9763 - 3679 = 6084 = 78^2
9768 - 8679 = 1089 = 33^2
9814 - 4189 = 5625 = 75^2
9845 - 5489 = 4356 = 66^2
9873 - 3789 = 6084 = 78^2
9878 - 8789 = 1089 = 33^2
9900 - 99 = 9801 = 99^2
9924 - 4299 = 5625 = 75^2
9955 - 5599 = 4356 = 66^2
9983 - 3899 = 6084 = 78^2
9988 - 8899 = 1089 = 33^2
10090 - 9001 = 1089 = 33^2
10100 + 101 = 10201 = 101^2
10148 + 84101 = 94249 = 307^2
10190 - 9101 = 1089 = 33^2
10290 - 9201 = 1089 = 33^2
10340 + 4301 = 14641 = 121^2
10390 - 9301 = 1089 = 33^2
10395 + 59301 = 69696 = 264^2
10403 + 30401 = 40804 = 202^2
10490 - 9401 = 1089 = 33^2
10590 - 9501 = 1089 = 33^2
10683 + 38601 = 49284 = 222^2
10690 - 9601 = 1089 = 33^2
10790 - 9701 = 1089 = 33^2
10890 - 9801 = 1089 = 33^2
10908 + 80901 = 91809 = 303^2
10980 + 8901 = 19881 = 141^2
10990 - 9901 = 1089 = 33^2
11138 + 83111 = 94249 = 307^2
11330 + 3311 = 14641 = 121^2
11385 + 58311 = 69696 = 264^2
11673 + 37611 = 49284 = 222^2
11970 + 7911 = 19881 = 141^2
12128 + 82121 = 94249 = 307^2
12320 + 2321 = 14641 = 121^2
12375 + 57321 = 69696 = 264^2
12663 + 36621 = 49284 = 222^2
12960 + 6921 = 19881 = 141^2
13118 + 81131 = 94249 = 307^2
13310 + 1331 = 14641 = 121^2
13365 + 56331 = 69696 = 264^2
13653 + 35631 = 49284 = 222^2
13950 + 5931 = 19881 = 141^2
14108 + 80141 = 94249 = 307^2
14300 + 341 = 14641 = 121^2
14355 + 55341 = 69696 = 264^2
14643 + 34641 = 49284 = 222^2
14940 + 4941 = 19881 = 141^2
15345 + 54351 = 69696 = 264^2
15633 + 33651 = 49284 = 222^2
15930 + 3951 = 19881 = 141^2
16335 + 53361 = 69696 = 264^2
16623 + 32661 = 49284 = 222^2
16920 + 2961 = 19881 = 141^2
17325 + 52371 = 69696 = 264^2
17613 + 31671 = 49284 = 222^2
17910 + 1971 = 19881 = 141^2
18315 + 51381 = 69696 = 264^2
18603 + 30681 = 49284 = 222^2
18900 + 981 = 19881 = 141^2
19305 + 50391 = 69696 = 264^2
20091 - 19002 = 1089 = 33^2
20147 + 74102 = 94249 = 307^2
20191 - 19102 = 1089 = 33^2
20291 - 19202 = 1089 = 33^2
20391 - 19302 = 1089 = 33^2
20394 + 49302 = 69696 = 264^2
20402 + 20402 = 40804 = 202^2
20491 - 19402 = 1089 = 33^2
20591 - 19502 = 1089 = 33^2
20682 + 28602 = 49284 = 222^2
20691 - 19602 = 1089 = 33^2
20791 - 19702 = 1089 = 33^2
20891 - 19802 = 1089 = 33^2
20907 + 70902 = 91809 = 303^2
20991 - 19902 = 1089 = 33^2
21137 + 73112 = 94249 = 307^2
21384 + 48312 = 69696 = 264^2
21672 + 27612 = 49284 = 222^2
22127 + 72122 = 94249 = 307^2
22374 + 47322 = 69696 = 264^2
22662 + 26622 = 49284 = 222^2
23117 + 71132 = 94249 = 307^2
23364 + 46332 = 69696 = 264^2
23652 + 25632 = 49284 = 222^2
24107 + 70142 = 94249 = 307^2
24354 + 45342 = 69696 = 264^2
24642 + 24642 = 49284 = 222^2
25344 + 44352 = 69696 = 264^2
25632 + 23652 = 49284 = 222^2
26334 + 43362 = 69696 = 264^2
26622 + 22662 = 49284 = 222^2
27324 + 42372 = 69696 = 264^2
27612 + 21672 = 49284 = 222^2
28314 + 41382 = 69696 = 264^2
28602 + 20682 = 49284 = 222^2
29304 + 40392 = 69696 = 264^2
30092 - 29003 = 1089 = 33^2
30146 + 64103 = 94249 = 307^2
30192 - 29103 = 1089 = 33^2
30292 - 29203 = 1089 = 33^2
30392 - 29303 = 1089 = 33^2
30393 + 39303 = 69696 = 264^2
30401 + 10403 = 40804 = 202^2
30492 - 29403 = 1089 = 33^2
30592 - 29503 = 1089 = 33^2
30681 + 18603 = 49284 = 222^2
30692 - 29603 = 1089 = 33^2
30792 - 29703 = 1089 = 33^2
30892 - 29803 = 1089 = 33^2
30906 + 60903 = 91809 = 303^2
30992 - 29903 = 1089 = 33^2
31136 + 63113 = 94249 = 307^2
31383 + 38313 = 69696 = 264^2
31671 + 17613 = 49284 = 222^2
32126 + 62123 = 94249 = 307^2
32373 + 37323 = 69696 = 264^2
32661 + 16623 = 49284 = 222^2
33116 + 61133 = 94249 = 307^2
33363 + 36333 = 69696 = 264^2
33651 + 15633 = 49284 = 222^2
34106 + 60143 = 94249 = 307^2
34353 + 35343 = 69696 = 264^2
34641 + 14643 = 49284 = 222^2
35343 + 34353 = 69696 = 264^2
35631 + 13653 = 49284 = 222^2
36333 + 33363 = 69696 = 264^2
36621 + 12663 = 49284 = 222^2
37323 + 32373 = 69696 = 264^2
37611 + 11673 = 49284 = 222^2
38313 + 31383 = 69696 = 264^2
38601 + 10683 = 49284 = 222^2
39303 + 30393 = 69696 = 264^2
40093 - 39004 = 1089 = 33^2
40145 + 54104 = 94249 = 307^2
40193 - 39104 = 1089 = 33^2
40293 - 39204 = 1089 = 33^2
40392 + 29304 = 69696 = 264^2
40393 - 39304 = 1089 = 33^2
40400 + 404 = 40804 = 202^2
40493 - 39404 = 1089 = 33^2
40593 - 39504 = 1089 = 33^2
40680 + 8604 = 49284 = 222^2
40693 - 39604 = 1089 = 33^2
40793 - 39704 = 1089 = 33^2
40893 - 39804 = 1089 = 33^2
40905 + 50904 = 91809 = 303^2
40993 - 39904 = 1089 = 33^2
41135 + 53114 = 94249 = 307^2
41382 + 28314 = 69696 = 264^2
41670 + 7614 = 49284 = 222^2
42125 + 52124 = 94249 = 307^2
42372 + 27324 = 69696 = 264^2
42660 + 6624 = 49284 = 222^2
43115 + 51134 = 94249 = 307^2
43362 + 26334 = 69696 = 264^2
43650 + 5634 = 49284 = 222^2
44105 + 50144 = 94249 = 307^2
44352 + 25344 = 69696 = 264^2
44640 + 4644 = 49284 = 222^2
45342 + 24354 = 69696 = 264^2
45630 + 3654 = 49284 = 222^2
46332 + 23364 = 69696 = 264^2
46620 + 2664 = 49284 = 222^2
47322 + 22374 = 69696 = 264^2
47610 + 1674 = 49284 = 222^2
48312 + 21384 = 69696 = 264^2
48600 + 684 = 49284 = 222^2
49302 + 20394 = 69696 = 264^2
50094 - 49005 = 1089 = 33^2
50144 + 44105 = 94249 = 307^2
50194 - 49105 = 1089 = 33^2
50294 - 49205 = 1089 = 33^2
50391 + 19305 = 69696 = 264^2
50394 - 49305 = 1089 = 33^2
50494 - 49405 = 1089 = 33^2
50594 - 49505 = 1089 = 33^2
50694 - 49605 = 1089 = 33^2
50794 - 49705 = 1089 = 33^2
50894 - 49805 = 1089 = 33^2
50904 + 40905 = 91809 = 303^2
50994 - 49905 = 1089 = 33^2
51134 + 43115 = 94249 = 307^2
51381 + 18315 = 69696 = 264^2
52124 + 42125 = 94249 = 307^2
52371 + 17325 = 69696 = 264^2
53114 + 41135 = 94249 = 307^2
53361 + 16335 = 69696 = 264^2
54104 + 40145 = 94249 = 307^2
54351 + 15345 = 69696 = 264^2
55341 + 14355 = 69696 = 264^2
56331 + 13365 = 69696 = 264^2
57321 + 12375 = 69696 = 264^2
58311 + 11385 = 69696 = 264^2
59301 + 10395 = 69696 = 264^2
60095 - 59006 = 1089 = 33^2
60143 + 34106 = 94249 = 307^2
60195 - 59106 = 1089 = 33^2
60295 - 59206 = 1089 = 33^2
60390 + 9306 = 69696 = 264^2
60395 - 59306 = 1089 = 33^2
60495 - 59406 = 1089 = 33^2
60595 - 59506 = 1089 = 33^2
60695 - 59606 = 1089 = 33^2
60795 - 59706 = 1089 = 33^2
60895 - 59806 = 1089 = 33^2
60903 + 30906 = 91809 = 303^2
60995 - 59906 = 1089 = 33^2
61133 + 33116 = 94249 = 307^2
61380 + 8316 = 69696 = 264^2
62123 + 32126 = 94249 = 307^2
62370 + 7326 = 69696 = 264^2
63113 + 31136 = 94249 = 307^2
63360 + 6336 = 69696 = 264^2
64103 + 30146 = 94249 = 307^2
64350 + 5346 = 69696 = 264^2
65340 + 4356 = 69696 = 264^2
66330 + 3366 = 69696 = 264^2
67320 + 2376 = 69696 = 264^2
68310 + 1386 = 69696 = 264^2
69300 + 396 = 69696 = 264^2
70096 - 69007 = 1089 = 33^2
70142 + 24107 = 94249 = 307^2
70196 - 69107 = 1089 = 33^2
70296 - 69207 = 1089 = 33^2
70396 - 69307 = 1089 = 33^2
70496 - 69407 = 1089 = 33^2
70596 - 69507 = 1089 = 33^2
70696 - 69607 = 1089 = 33^2
70796 - 69707 = 1089 = 33^2
70896 - 69807 = 1089 = 33^2
70902 + 20907 = 91809 = 303^2
70996 - 69907 = 1089 = 33^2
71132 + 23117 = 94249 = 307^2
72122 + 22127 = 94249 = 307^2
73112 + 21137 = 94249 = 307^2
74102 + 20147 = 94249 = 307^2
80097 - 79008 = 1089 = 33^2
80141 + 14108 = 94249 = 307^2
80197 - 79108 = 1089 = 33^2
80297 - 79208 = 1089 = 33^2
80397 - 79308 = 1089 = 33^2
80497 - 79408 = 1089 = 33^2
80597 - 79508 = 1089 = 33^2
80697 - 79608 = 1089 = 33^2
80797 - 79708 = 1089 = 33^2
80897 - 79808 = 1089 = 33^2
80901 + 10908 = 91809 = 303^2
80997 - 79908 = 1089 = 33^2
81131 + 13118 = 94249 = 307^2
82121 + 12128 = 94249 = 307^2
83111 + 11138 = 94249 = 307^2
84101 + 10148 = 94249 = 307^2
90098 - 89009 = 1089 = 33^2
90140 + 4109 = 94249 = 307^2
90198 - 89109 = 1089 = 33^2
90298 - 89209 = 1089 = 33^2
90398 - 89309 = 1089 = 33^2
90498 - 89409 = 1089 = 33^2
90598 - 89509 = 1089 = 33^2
90698 - 89609 = 1089 = 33^2
90798 - 89709 = 1089 = 33^2
90898 - 89809 = 1089 = 33^2
90900 + 909 = 91809 = 303^2
90998 - 89909 = 1089 = 33^2
91130 + 3119 = 94249 = 307^2
92120 + 2129 = 94249 = 307^2
93110 + 1139 = 94249 = 307^2
94100 + 149 = 94249 = 307^2

DefDbl A-Z
Dim crlf\$

crlf = Chr(13) + Chr(10)
Text1.Text = ""
Form1.Visible = True

For n = 1 To 100000
ns\$ = LTrim(Str(n))
nrs\$ = ""
For i = 1 To Len(ns)
nrs = Mid(ns, i, 1) + nrs
Next
nr = Val(nrs)
sq = n + nr: sr = Int(Sqr(sq) + 0.5)
If sr * sr = sq Then
Text1.Text = Text1.Text & n & " + " & nr & " = " & sq & " = " & sr & "^2" & crlf
End If
sq = n - nr
If sq > 0 Then
sr = Int(Sqr(sq) + 0.5)
If sr * sr = sq Then
Text1.Text = Text1.Text & n & " - " & nr & " = " & sq & " = " & sr & "^2" & crlf
End If
End If
DoEvents
Next

Text1.Text = Text1.Text & crlf & " done"

End Sub

 Posted by Charlie on 2018-07-28 11:43:29

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