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2x4 = 4x2 (Posted on 2023-10-04) Difficulty: 3 of 5
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The 2x3 grid given above has an interesting property: If you read horizontally, you get 264 and 200, where 264×200 = 52800. If you read vertically, you get 22, 60 and 40, where 22×60×40 = 52800.

So the horizontal product is the same as the vertical product. Find a 2×4 grid with the same property using 8 different digits.

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

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution computer and visual selection Comment 2 of 2 |
clearvars,clc
for a=123:9999
  top=sprintf('%04d',a);
  if isequal(top(3:4),'00') % for progress indication only
    disp(top)
  end
  for b=123:9999
    p=a*b;
    bot=sprintf('%04d',b);
    p2=prod(10*(top-'0')+bot-'0');
    if p==p2
      disp(' ')
      disp(top)
      disp(bot)
      disp(' ')
    end
  end
end


finds the following sets that meet the multiplication criterion, but have not been checked for repeated digits.

 
1395
1100
 
1485
1584
 
1584
1485
 
 
1595
1800
 
1680
0248
 
 
1694
1680
 
1768
2835
 
 
1768
2880
 
2288
1680
 
2368
1743
 
 
2376
1323
 
2496
2365
 
2646
1323
 
 
2646
1350
 
2736
1281
 
 
2755
1680
 
 
2765
1950
 
 
2793
1680
 
2835
1024
 
 
2835
1155
 
3660
0124
 
 
3660
0165
 
 
3660
0217
 
3795
3024
 
3828
1798
 
4389
2880
 
4464
1025
 
4725
0704
 
5475
1530
 
 
5499
3710
 
5568
2860
 
5600
5700
 
5767
3339

6696
3220
 
6700
6800
 
6885
3150
 
 
6889
6336
 
7560
0299
 
7896
4440
 
9568
2950
 
9840
0288
 

Only one does not repeat any digit:

 
2793
1680

2793 * 1680 = 4692240

21 * 76 * 98 * 30 = 4692240

  Posted by Charlie on 2023-10-04 09:14:50
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