Skip to main content

King's Maths School

Challenge 372: Is it an Integer?

Dr Reasoner claims to have found an expression that always gives an integer value whatever integer is used for n. Prove her claim!

Dr Reasoner claims that the expression

5n3−11n6\frac{5n^3-11n}{6}

takes an integer value for any integer value of n. 

Prove her claim!