Fibonacci sequence

There are 30 NRICH Mathematical resources connected to Fibonacci sequence
Golden Fractions
problem

Golden Fractions

Age
16 to 18
Challenge level
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Find the link between a sequence of continued fractions and the ratio of succesive Fibonacci numbers.
Sheep Talk
problem

Sheep Talk

Age
7 to 11
Challenge level
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In sheep talk the only letters used are B and A. A sequence of words is formed by following certain rules. What do you notice when you count the letters in each word?
Golden Fibs
problem

Golden Fibs

Age
16 to 18
Challenge level
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When is a Fibonacci sequence also a geometric sequence? When the ratio of successive terms is the golden ratio!
Fibonacci Factors
problem

Fibonacci Factors

Age
16 to 18
Challenge level
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For which values of n is the Fibonacci number fn even? Which Fibonnaci numbers are divisible by 3?
Ordered Sums
problem

Ordered Sums

Age
14 to 16
Challenge level
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Let a(n) be the number of ways of expressing the integer n as an ordered sum of 1's and 2's. Let b(n) be the number of ways of expressing n as an ordered sum of integers greater than 1. (i) Calculate a(n) and b(n) for n<8. What do you notice about these sequences? (ii) Find a relation between a(p) and b(q). (iii) Prove your conjectures.
Stringing it Out
problem

Stringing it Out

Age
14 to 16
Challenge level
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Explore the transformations and comment on what you find.
LOGO Challenge - Circles as bugs
problem

LOGO Challenge - Circles as bugs

Age
11 to 16
Challenge level
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Here are some circle bugs to try to replicate with some elegant programming, plus some sequences generated elegantly in LOGO.
1 Step 2 Step
problem

1 Step 2 Step

Age
11 to 14
Challenge level
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Liam's house has a staircase with 12 steps. He can go down the steps one at a time or two at time. In how many different ways can Liam go down the 12 steps?
Gnomon dimensions
problem

Gnomon dimensions

Age
14 to 16
Challenge level
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These gnomons appear to have more than a passing connection with the Fibonacci sequence. This problem ask you to investigate some of these connections.