Stage: 5 Challenge Level: 
Why do this problem ?
For practice in factorising polynomials.Key question
What is the highest power of 5 we can find using a calculator?Can we factorise this expression to get factors involving smaller powers of 5, so that all the powers of 5 can be found using a calculator?
Howdo you know if a number is divisible by 3?
Factors and multiples. Index notation/Indices. Pythagoras' theorem. Identities. Modulus arithmetic. Working systematically. Long problems. Mathematical reasoning & proof. Quadratic equations. Factorisation (algebraic).
Published June 1998.
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