The euro note
The number on a bank note (here : Y00309901015) s made up of a letter and 11 digits.
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The letter identifies for which country the bill was printed.
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The whole number must obey the following rules :
Example for Y00309901015.
Replace the letter with its place in the alphabet. Rewrite the number with the letter replaced by its 'place value'. Work out S, the sum of the digits of n. Calculate the remainder when S is divided by 9. |
Y = 25 n = 2500309901015 S = 2+5+3+9+9+1+1+5 = 35 35 = 9 x 3 + 8 |