Yan Cui

I help clients go faster for less using serverless technologies.

#### Problem

An irrational decimal fraction is created by concatenating the positive integers:

0.123456789101112131415161718192021…

It can be seen that the 12^{th}digit of the fractional part is 1.

If d_{n}represents the n^{th}digit of the fractional part, find the value of the following expression.

d_{1}x d_{10}x d_{100}x d_{1000}x d_{10000}x d_{100000}x d_{1000000}

#### Solution

`A pretty straight forward solution, the only trick is to turn the sequence of natural numbers 1, 2, 3, … 11, 12, 13.. into a continuous sequence of individual numbers. I did so by taking each number and turning it into a string array of its digits (e.g. 11 –> {"1"; "1"}) and concatenating these arrays using Seq.collect.`

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