n n\,n is an integer. Prove algebraically that the sum of n(n+1)n(n + 1)n(n+1) and n+1n + 1n+1 is always a square number. Hence find the sum when n=6n = 6n=6.
207 exam-style questions on OCR GCSE Maths Proof. Each one has a worked solution and a mark scheme showing where the marks go.