In how many ways can you arrange the five numbers 1, 2, 3, 4, 5?
Think about the number of choices: five for the first choice, four for the second, and so on, so the number of ways is:
5 \times 4 \times 3 \times 2 \times 1 = 120
This calculation is called 5 factorial and is written 5!
In general for any positive integer n , n! = n(n-1)(n-2)... 1 \quad and 0! = 1.
Think about the number of choices: five for the first choice, four for the second, and so on, so the number of ways is:
5 \times 4 \times 3 \times 2 \times 1 = 120
This calculation is called 5 factorial and is written 5!
In general for any positive integer n , n! = n(n-1)(n-2)... 1 \quad and 0! = 1.
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This question appears in the following syllabi:
Syllabus | Module | Section | Topic | Exam Year |
---|---|---|---|---|
AQA A-Level (UK - Pre-2017) | S1 | The Binomial Distribution | Combinations | - |
AQA AS Maths 2017 | Pure Maths | Binomial Expansion | Permutations and Combinations | - |
AQA AS/A2 Maths 2017 | Pure Maths | Binomial Expansion | Permutations and Combinations | - |
CBSE XI (India) | Algebra | Permutation and Combinations | Factorial | - |
CCEA A-Level (NI) | S1 | The Binomial Distribution | Combinations | - |
CIE A-Level (UK) | S1 | The Binomial Distribution | Combinations | - |
Edexcel A-Level (UK - Pre-2017) | S2 | The Binomial Distribution | Combinations | - |
Edexcel AS Maths 2017 | Statistics | Statistical Distributions | Permutations and Combinations | - |
Edexcel AS/A2 Maths 2017 | Statistics | Statistical Distributions | Permutations and Combinations | - |
I.B. Higher Level | 7 | The Binomial Distribution | Combinations | - |
Methods (UK) | M15 | The Binomial Distribution | Combinations | - |
OCR A-Level (UK - Pre-2017) | S1 | The Binomial Distribution | Combinations | - |
OCR AS Maths 2017 | Statistics | Discrete and Binomial Distributions | Permutations and Combinations | - |
OCR MEI AS Maths 2017 | Statistics | The Binomial Distribution | Permutations and Combinations | - |
OCR-MEI A-Level (UK - Pre-2017) | S1 | The Binomial Distribution | Combinations | - |
Pre-U A-Level (UK) | Prob | The Binomial Distribution | Combinations | - |
Universal (all site questions) | B | The Binomial Distribution | Combinations | - |
WJEC A-Level (Wales) | S1 | The Binomial Distribution | Combinations | - |