The factorial of a number is the product of all positive integers up to that number. For instance, the factorial of 5 (written as 5!) is calculated as:
5! = 5 × 4 × 3 × 2 × 1 = 120
Now, let’s calculate the factorial of 20, which is written as 20!. It’s the product of all integers from 1 to 20:
20! = 20 × 19 × 18 × 17 × 16 × 15 × 14 × 13 × 12 × 11 × 10 × 9 × 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1
Calculating this yields:
20! = 2,432,902,008,176,640,000
So, the factorial of 20 is an incredibly large number: 2,432,902,008,176,640,000. Factorials grow very rapidly, which is why even relatively small numbers like 20 can result in such large products. Factorials are commonly used in permutations, combinations, and various areas of mathematics and computer science.