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$

Private Sub Form_Load()

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