ERJ Brainteaser: August
30 Aug 2024
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For some great answering, including supplying the only correct reply to extra tricky Q1, it’s congratulations to Michele Girardi of Mastaf SpA, our new Brainiac of the Month
Question 4: You cannot be series XXI
23, 57, 1113, _?_ ...
Answer: These are sequential pairs of prime numbers, so the next number in this series would be 1719, then 2329 etc. Very well done to: John Bowen, consultant, Bromsgrove, UK; Stephan Paischer, head of product management and market intelligence, Semperit AG Holding, Vienna, Austria; Kamila Staszewska, R&D / quality lead, Abcon Industrial Products Ltd, Cootehill, Co. Cavan, Ireland; Michele Girardi, quality manager, Scame Mastaf SpA, Suisio, Italy; Sudi Sudarshan, principal consultant, Global Mobility Strategies, USA; and everyone else who had a go.
Question 3: High five
Fill in the blanks using +, -, *, or / to make this equation valid. You may also add parentheses if necessary.
5 _ 5 _ 5 _ 5 _ 5 = 24
Answer: Readers came up with a nice variety of answers to this question (see Solutions below). Very well done to: Simon Winfield, director, MacLellan Rubber Ltd, Wednesfield, Wolverhampton, UK; Kamila Staszewska, R&D / quality lead, Abcon Industrial Products Ltd, Cootehill, Co. Cavan, Ireland; Andrew Knox, Rubbond International, Ohé en Laak, The Netherlands; Kate Burns, senior technologist and regulatory officer, Prisma Colour Ltd, Birch Vale, High Peak, Derbyshire; Sabit Karayel, compound development manager, Petlas Lastik Sanayi ve Ticaret A?, Türkiye; Michele Girardi, quality manager, Scame Mastaf SpA, Suisio, Italy; Semih Öngir, maintenance manager, Petlas Lastik Sanayi ve Ticaret A?, Türkiye.
An extra and exceptional well done to Michele Girardi, who cleverly deduced the answer to Q1 - one of our toughest ever teasers: The missing number is 47. The series is 29, 30, 50; 47; 47, 79. Referring to sports and Olympics: The bronze medals are made of Copper, Tin and Zinc, whose atomic numbers are 29,30,50; the Silver medals are made of Silver whose atomic number is 47; and the Gold medals are made of Silver plated with Gold, whose atomic numbers are 47 and 79.
SOLUTIONS
Simon Winfield
5 x 5 x 5 – 5 / 5 = 24
5 x 5 x 5 = 125 – 5 = 120 / 5 = 24
Kamila Staszewska
The answer can be: (5 * 5 * 5 - 5) / 5 = 24
Andrew Knox
Answer: ((5*5*5)-5)/5=24
Dr Kate Burns
[(5*5*5)-5]/5
= (125 -5)/5
=120/5
=24
Sabit Karayel
((5*5*5)-5)/5=24
Michele Girardi
(5x5x5 -5 )/5 = 24
Semih Öngir
5*(5-(5/5)/5)=24
Question 2: Millennium bug
Fill in the missing years in this millennium sequence:
2307, 2417, 2527, 2637, _, _, _.
Answer: The rest of the sequence is: 2747, 2857, 2967 (add110), as neatly worked out by: Andrew Knox, Rubbond International, Ohé en Laak, The Netherlands; John Bowen, consultant, Bromsgrove, UK; Sabit Karayel, compound development manager, Petlas Lastik, Saniya ve Ticaret AS, Turkey; Michele Girardi, quality manager, Scame Mastaf SpA, Suisio, Italy; Sudi Sudarshan, principal consultant, Global Mobility Strategies, USA. Well done to all and everyone else who had a go.
(ps The new clue added to Q1 might help to reveal the answer)
Question 1: Tricky teaser
Complete the series
29, 30, 50; 47; ?, 79.
Clues: Sport, ----fish, Bronze...
Email your answer: correct replies next Friday*.
*As this teaser proved even trickier than we imagined, we'll run as a bonus question until we get a few correct answers - hopefully.