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计算大数阶乘，显示结果和科学计数法。
Factorial N
3,628,800
公式
## Factorial, Permutations, and Combinations ### Factorial **n! = n × (n-1) × (n-2) × ... × 2 × 1** 0! = 1 by convention. ### Permutations (order matters) **P(n, r) = n! / (n-r)!** Number of ways to arrange r items from n distinct items. ### Combinations (order doesn't matter) **C(n, r) = n! / (r! × (n-r)!)** Number of ways to choose r items from n without regard to order.
计算示例
Calculate 10!, P(10,3), and C(10,3).
- 0110! = 3,628,800
- 02P(10,3) = 10!/7! = 10×9×8 = 720
- 03C(10,3) = 720/3! = 720/6 = 120
常见问题
What is a factorial?
n factorial (n!) is the product of all positive integers from 1 to n. For example, 5! = 120. By convention, 0! = 1.
What is the difference between permutations and combinations?
Permutations count ordered arrangements (ABC is different from BCA). Combinations count unordered selections (ABC is the same as BCA).
Why does 0! equal 1?
By convention and to make formulas work consistently. There is exactly one way to arrange zero objects: do nothing.
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