Factorial+Review

n factorial (n!) means that you multiply n by all positive integers smaller than n, not including 0.
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Example:
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Example:
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Don't forget that there is also a way to simplify the expression, making it easier to solve without a calculator.

Summation Notation
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Writing this notation is the same as taking the sum of f(i), where i ranges from a to b.

Example:
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Binomial Theorem
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Why Does it Work?
If we break down the Theorem, then we can find that it is related to the Summation Notation.