#73 Changing guard
Fifteen members of the King鈥檚 99th Dragoons are standing on parade. 鈥淩ight turn!鈥� screams the sergeant, and each soldier makes a 90掳 turn. Unfortunately, many of the squad struggle to know their left from their right. After this manoeuvre, five soldiers end up facing left, including Private Perkins, who is in the middle of the row.
X X X X X X X P X X X X X X X
Any soldier that ends up face to face with another soldier now does a 180掳 turn. This awkward ritual continues until no soldier can see another soldier鈥檚 face. Can we be sure that Perkins will end up facing the right way?
Answer next week
#72 A long lane
Solution
Professor Lemma would need to move to number 756.
If Numero鈥檚 house number is N and Lemma鈥檚 is L, we are told that N x L = k x (L + N), where k is a whole number.
With a bit of rearranging we get: L = kN 梅 (N 鈥� k)
We want L to be as large as possible, and therefore N 鈥� k must be as small as possible, i.e. N 鈥� k = 1.
So k = N 鈥� 1, and hence L = (N 鈥� 1) x N.
If N = 28, L = 756.
Quick quiz #65
1 In 1976, research chemist Shashikant Phadnis misunderstood instructions to test a chlorinated compound of sucrose and instead tasted it. What did he then discover?
2 What did an odd bit of 鈥渟cruff鈥� in her radio telescope read-out lead astronomer Jocelyn Bell Burnell to discover in 1967?
3 The phenomenon of burrs sticking to his clothes inspired George de Mestral to create which material?
4 Which lightweight, superstrong material was invented by DuPont chemist Stephanie Kwolek as her group hunted for a fibre to replace the steel wires used in car tyres?
5 Whose patent count did Shunpei Yamazaki exceed in 2003 to become the most prolific inventor?
Answers
1 That it was extraordinarily sweet; it was sucralose, which is now used as an artificial sweetener
2 Pulsars. The scruff was the fast, repeating signals of these rapidly rotating neutron stars
3 Velcro
4 Kevlar
5 Thomas Edison鈥檚