Question Video: Evaluating Factorials | Nagwa Question Video: Evaluating Factorials | Nagwa

Question Video: Evaluating Factorials Mathematics • Second Year of Secondary School

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Evaluate 4!.

01:23

Video Transcript

Evaluate four factorial.

We begin by recalling that the factorial of any positive integer 𝑛 is the product of all the positive integers less than or equal to 𝑛. This means that 𝑛 factorial is equal to 𝑛 multiplied by 𝑛 minus one multiplied by 𝑛 minus two and so on multiplied by two multiplied by one. Four factorial is therefore equal to four multiplied by three multiplied by two multiplied by one.

As multiplication is commutative, we can multiply our integers in any order. For example, four multiplied by three is equal to 12. Two multiplied by one is equal to two. And then multiplying 12 by two gives us an answer of 24. Alternatively, we could multiply four by three, giving us 12, then multiply this by two, giving us 24, and finally multiplying 24 by one gives us a final answer of 24. This confirms that four factorial is equal to 24.

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