Factorials

There are 16 NRICH Mathematical resources connected to Factorials

problem

Seriesly

Age

16 to 18

Challenge level

Prove that k.k! = (k+1)! - k! and sum the series 1.1! + 2.2! + 3.3! +...+n.n!

problem

Forgotten number

Age

11 to 14

Challenge level

I have forgotten the number of the combination of the lock on my briefcase. I did have a method for remembering it...

problem

Factorial

Age

14 to 16

Challenge level

How many zeros are there at the end of the number which is the product of first hundred positive integers?

problem

Factoring factorials

Age

11 to 14

Challenge level

Find the highest power of 11 that will divide into 1000! exactly.

Placeholder: several colourful numbers

article

Binomial coefficients

An introduction to the binomial coefficient, and exploration of some of the formulae it satisfies.

article

The harmonic triangle and pascal's triangle

The harmonic triangle is built from fractions with unit numerators using a rule very similar to Pascal's triangle.