Maths magic!

Who's into maths here? Here's a good maths question I found from my e-mail.

Scenario:
There is a bus with 7 girls inside,
Each girl has 7 bags,
Inside each bag, there are 7 Big cats,
Each Big cat has 7 small cats,
All cats have 4 Legs each!

Question: How many Legs are there inside the bus?

The total number of Legs would be the password for this file:
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