Topic Details (Notes format)

How to Use the Factorial Function (n!)

Subject: Mathematics

Book: Maths Mastery

The factorial of n, denoted n!, is the product of all positive integers up to n (e.g., 5!=120). Factorials appear in permutations, combinations (nCr = n! / [r!(n-r)!]), and expansions. For large n, the numbers grow rapidly. Factorials are key to gamma functions, probability distributions (Poisson), and combinatorial logic. Understanding them fosters quick problem-solving in arrangement tasks, advanced series expansions, or bridging to continuous extensions in advanced calculus or physics contexts.

Practice Questions

What is the LCM of 15 and 20?

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If a + b = 10 and ab = 21, what is the value of a^2 + b^2?

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A number is increased by 20% and then decreased by 10%. What is the net change?

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What is the sum of all odd numbers from 1 to 99?

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A sum of money triples itself in 12 years at simple interest. What is the rate of interest per annum?

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A cube has a side length of 4 cm. What is its volume?

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A cone has a base radius of 7 cm and height of 24 cm. What is its volume?

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If the perimeter of a square is 40 cm, what is the area of the square?

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If x:y = 2:3 and z:y = 4:3, what is x:z?

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If the product of two numbers is 120 and their sum is 26, what are the numbers?

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