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

If x:y = 4:5 and y:z = 2:3, what is x:z?

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

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If sin(A) = 3/5 and cos(B) = 5/13, where A and B are acute angles, what is sin(A+B)?

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If x + 1/x = 5, what is the value of x^2 + 1/x^2?

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If sin(θ) = 3/5 and θ is an acute angle, what is tan(θ)?

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If the ratio of two numbers is 3:5 and their HCF is 4, what are the numbers?

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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 car travels 240 km in 4 hours. What is its average speed?

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

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If the sum of the angles of a polygon is 1080°, how many sides does the polygon have?

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