✓ Question 5: 13
Round 1 completed
Next: round 2, figures and patterns
5 questions with shapes, arrows and dots. Look for what changes from one figure to the next.
Why, in question 5: Which number comes next?
The answer is 13. Each number is the sum of the two before it: 1 + 1 = 2, 1 + 2 = 3, 2 + 3 = 5, 3 + 5 = 8 and 5 + 8 = 13.
The Fibonacci sequence
This is one of the most famous sequences in mathematics. It is named after Leonardo of Pisa, known as Fibonacci, who presented it in a book from 1202, in a problem about rabbit breeding.
The sequence appears in several places in nature. In many sunflowers, the seeds form spirals in two directions, and the number of spirals in each direction is often a pair of neighbouring numbers in the sequence, such as 34 and 55.
Another curiosity: dividing each number by the previous one, the result gets closer and closer to a special value, called the golden ratio, which is often cited in art and architecture.
To recognise this kind of rule, check whether a number can be formed from the ones before it, not just the last one. Adding the two previous numbers is the most common way.
