#59 Celebrate the differences
Complete the diagram so that each of the nine circles contains a different digit from 1 to 9. Whenever two circles are connected by a straight line, the difference between the two numbers must be three or more (e.g. 5, 6, 8 and 9 can鈥檛 be connected to 7). The bottom-left square isn鈥檛 1.
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#58 Lego lockdown
There are 89 ways of combining the bricks to make a row of length 10. The combinations for length n follow the Fibonacci sequence, in which each number in the sequence is the sum of the previous two:
1, 2, 3, 5, 8, 13, 21, 34, 55, 89
This is because sequences of length n can be created either by adding a 2-brick to the end of each sequence that has length n-2, or by adding a 1-brick at the end of each sequence that has length n-1. The total number of combinations can therefore be obtained by adding these two smaller numbers together.
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Quick quiz #51
1 Their employment of whip-like cells known as flagella in reproduction suggests animals share a common ancestor with which other traditional kingdom of life?
2 The Frenchman Jean-Henri Fabre wrote an influential 1912 book, still in print, called Social Life in the鈥� what?
3 What first did Harriet Quimby achieve over 59 minutes on 16 April 1912?
4 In what area of scientific endeavour might you find yourself operating on bras and kets?
5 Described as a 鈥渕agic sheet of paper that can perform calculations and recalculations鈥� on its release in 1979, how might we describe VisiCalc today?
Answers on page 54
Quick quiz #51
Answers
1 Fungi. Sperm are flagella, as are spores
2 Insect World
3 She became the first woman to fly an aeroplane across the English Channel
4 In quantum theory; they are a common notation for vectors describing quantum states
5 A spreadsheet program; it was the first such developed for a PC