#143 X marks the Spot
Now that poor Spot has gone to that great kennel in the sky, I have decided to bury him under a new square patio, using square tiles that are all the same size. The tiles along the two diagonals are to be black to form an X that marks his final resting place, and the rest of the tiles will be white.
I went to the builders鈥� merchant to buy the tiles, but when I arrived I had forgotten how many white tiles I needed. Was it 691? Or 916? Or something else? All I knew for sure was that the number of white tiles was a permutation of the three digits 1, 6 and 9.
I couldn鈥檛 even remember if the whole patio needed an even or an odd number of tiles. How many white tiles did I need? And how many black?
Solution next week
#142 Simultaneous pleasure
Solutions
1 The pen is 95p, the pencil 5p. The trap of instinctively answering 90p/10p has become a notorious case study in psychology.
2 Twelve cows, eight chickens.
Quick quiz #131
1 Astronomical objects with a known luminosity that can be used to calculate galactic distances are called what?
2 The name of which genus of dinosaurs roughly translates as 鈥渟wift seizer鈥�?
3 Name the country that contains more glacial ice than any other nation outside the polar regions.
4 How many chemical elements make up the lanthanide series, including lanthanum itself?
5 What did Arno Penzias and Robert Wilson accidentally detect in 1964?
Answers
1 Standard candles
2 Velociraptor
3 Pakistan. It has more than 7000 glaciers
4 15
5 The cosmic microwave background, which is remnant radiation from the big bang