That's a long one....isn't it?

Algebra Level 4

Let $$P(x) = x^6 + ax^5 + bx^4 + cx^3 + dx^2 + ex +f$$ be a polynomial such that

$$P(1) =1$$ , $$P(2) = 2$$ , $$P(3) = 3$$ , $$P(4) = 4$$ , $$P(5) = 5$$ and $$P(6) = 6$$.

Then find the value of $$P(7)$$.

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