Stage: 5 Challenge Level: 
In the Fibonacci sequence each term is the sum of the two terms before it:
1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144...
Where do the even numbers come in the sequence?
Is there a pattern? Why?
Which Fibonacci numbers are divisible by 3?
Prove general results for the occurrence of even Fibonacci numbers in the sequence and for the occurrence of multiples of 3.
Stage 5 - Reviewed 2012. Manipulating algebraic expressions/formulae. Making and proving conjectures. Golden ratio. Generalising. Mathematical reasoning & proof. Fibonacci sequence. Polynomials. Factorisation (algebraic). Interactivities.
Published January 2004.
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