Try this.

I got an email earlier today and i felt it was pretty interesting.

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How many minutes or hours do you need to solve the puzzle?
It is said that engineers take 3 minutes to resolve this, architects 3hours and doctors 6 hours.

Where do you rank?
If you can get what the 6th number is,
you'll be able to open the excelfile.

Once you discover it, put your name, save it and send it on.

So…what is the 6th number in this string of numbers : 1, 2, 6, 42, 1806,___???

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Well the excel sheet simply contains all the names of the people who solved the puzzle.