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Digits of N^3 (Posted on 2024-04-25) Difficulty: 3 of 5
Determine a positive integer N such that the digits of N combined with the digits of N^2 are exactly the digits of N^3.

Extra credit: Find additional solutions, other than multiples of 10.

See The Solution Submitted by K Sengupta    
Rating: 5.0000 (1 votes)

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Some Thoughts Some solutions Comment 2 of 2 |
I assumed that "exactly" meant not only the same digits, but also the same number of instances for each digit.  Also, since for every N which solves, N*10^k will also solve, so I ignored any solution ending in zero, going for the extra credit.

N values up to 10^8  with my definition of "exact" and no trailing zeros:
[6894, 579492, 730971, 2292309, 2906289, 5324499, 5920119, 7292088, 7893621, 7934391, 8250237, 8494146, 9419976, 22716252, 23488173, 24272199, 24426189, 24933087, 27130293, 27575037, 28274238, 30828231, 31052907, 48755196, 52094736, 52235892, 53376966, 53547345, 54022374, 54542646, 57842469, 60228279, 61306623, 66317535, 71397864, 71465994, 72034776, 74244906, 74695122, 75395682, 76813065, 77984271, 82153485, 82500435, 82506717, 84380958, 87264504, 87907491, 89179353, 89233416, 90815346, 93047805, 93138201, 93215655, 93641004, 94235976, 94361211, 98219016, 98474931, 98869932]

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 N          N^2             N^3
6894    47527236       327652764984
579492  335810978064   194599775300263488
730971  534318602841   390571403437288611
2292309 5254680551481  12045351520284859629
2906289 8446515751521  24548015816972215569
5324499 28350289601001 150951088630240223499
5920119 35047808974161 207487199816301045159
7292088 53174547399744 387753478999104425472
7893621 62309252491641 491845623962319722061
7934391 62954560540881 499506098564521338471
8250237 68066410556169 561564018827696062053
8494146 72150516269316 612857019166945424136
9419976 88735947840576 835890498995477746176
22716252 516028104927504  11722224470615622595008
23488173 551694270877929  12958290477489658233717
24272199 589139644295601  14299714685132042296599
24426189 596638709063721  14573609872306462189269
24933087 621658827349569  15499873626624783289503
27130293 736052798265849  19969328080422375263757
27575037 760382665551369  20967580136737625575653
28274238 799432534480644  22603345744848934849272
30828231 950379826589361  29298528831836763050391
31052907 964283033150649  29943791350105020386643
48755196 2377069136998416 115894471679908623769536
52094736 2713861518909696 141377899368159620960256
52235892 2728588413035664 142530249655782336852288
53376966 2849100499365156 152076340485196953396696
53547345 2867318156549025 153537274553494651088625
54022374 2918416892595876 157659808859732244129624
54542646 2974900232681316 162258930276454649402136
57842469 3345751220015961 193526511225485403647709
60228279 3627445591301841 218474805130247252961639
61306623 3758502023664129 230421066609513835226367
66317535 4398015448476225 291665543434862748105375
71397864 5097654983762496 363961677249596897708544
71465994 5107388298408036 365004581489698910327784
72034776 5189008953370176 373789097618015073240576
74244906 5512306066948836 409260645783846035629416
74695122 5579361250594884 416751069295257432955848
75395682 5684508864245124 428587422654806539154568
76813065 5900246954694225 453216052846979560049625
77984271 6081546523401441 474264972180045816734511
82153485 6749195097645225 554469898216470527359125
82500435 6806321775189225 561524507203083269812875
82506717 6807358350118089 561652788910780085703813
84380958 7120146072997764 600804746739489258177912
87264504 7615093658366016 664527371010855836696064
87907491 7727726973915081 679325089409897217771771
89179353 7952957001498609 709239559830465981019977
89233416 7962602531029056 710530224093968662135296
90815346 8247427069099716 748992942890056617041736
93047805 8657894015318025 805598034047978603185125
93138201 8674724485516401 807948232751648145134601
93215655 8689158337079025 809965585789532102136375
93641004 8768637630128016 821104031397368066768064
94235976 8880419172672576 836854968025912727794176
94361211 8904038141386521 840195821811421340636931
98219016 9646975104008256 947516402092188560196096
98474931 9697312035454761 954942133576877143096491
98869932 9775263453684624 966479632947883924325568

-----------
sols = []
for n in range(1, 100000000):
    if n%10 == 0:
        continue
    a = ''.join(sorted(( str(n) + str(n**2) )))
    b = ''.join(sorted(( str(n**3) )))
    if a == b:
        print(n, n**2, n**3)
        sols.append(n)

  Posted by Larry on 2024-04-25 11:18:56
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