H. E. Dudeney, Amusements in Mathematics (1917) No. 126 · Puzzles · Arithmetical puzzles
Simple Multiplication
If we number six cards 1, 2, 4, 5, 7, and 8, and arrange them on the table in this order:--
1 4 2 8 5 7
We can demonstrate that in order to multiply by 3 all that is necessary is to remove the 1 to the other end of the row, and the thing is done. The answer is 428571. Can you find a number that, when multiplied by 3 and divided by 2, the answer will be the same as if we removed the first card (which in this case is to be a 3) From the beginning of the row to the end?
H. E. Dudeney, Amusements in Mathematics (1917) · No. 126
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