"First, I wrote down the 3 times table
3X1=3
3X2=6
3X3=9
3X4=12
3X5=15
3X6=18
3X7=21
3X8=24
3X9=27
Then, I realised that i didn't need 3X10 because I already have one of every number.
After, I saw the 1, I needed 3 times _ = a number that ends with 1 so of course, 3X7, which is 21 so E is seven. Next, I put a 7 at the bottom e because e is 7, so E-2=5 so the next number must end with a 5. After that, I realised 3X5=15 so D is 5 so the bottom D is also 5 but minus 1 because 15 starts with a 1,that means the next number must end with a 4 so 3X8=24 so C is 8 and I put it on the bottom C, so C-2=6. Next, I did 3X2=6 so B is 2 than the bottom D is also two. After, I noticed that the next letter must end with a 2 so 3X4=12, that means A is 4. Finally, the first digit is 1 so it's:
1 4 2 8 5 7
X3
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4 2 8 5 7 1"