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-- An irrational decimal fraction is created by concatenating the positive integers:
--
-- 0.123456789101112131415161718192021...
--
-- It can be seen that the 12th digit of the fractional part is 1.
--
-- If dn represents the nth digit of the fractional part,
-- find the value of the following expression.
--
-- d1 × d10 × d100 × d1000 × d10000 × d100000 × d1000000
-- main = print (1 + sum [9 * 10 ^ i | i <- [0..5]])
main = do
print (product [champernowne !! (10 ^ i - 1) | i <- [0..6]])
champernowne = concat [showNbr n | n <- [1..]]
showNbr :: Integer -> [Integer]
showNbr x
| x < 10 = [x]
| otherwise = showNbr (x `div` 10) ++ [x `mod` 10]
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