# ERJ Brainteaser: February

26 Feb 2024

Each month, ERJ sets a weekly brainteaser, with questions of varying degrees of difficulty. Readers supplying the most accurate (and stylish) answers are then considered for the prestigious **Brainiac of the Month** title.

Question 3: **Missing number**

37, 10, 82

29, 11, 47

96, 15, 87

42, ?, 15

Email your answer: correct replies on Friday.

Question 2: **This is not easy**

**Answer**: Extremely well done to this elite group, who provided the correct answer **8,200,** as well as some helpful comments (see Solutions below) here & there: **David Mann**, Polymer Business Development (retired), UK; **Michele Girardi**, quality manager, Scame Mastaf SpA, Suisio, Italy; **Maurizio Bolognesi**, technical manager, Silikoneurope Srl, Loiano, Bologna, Italy; **Andrew Knox**, Rubbond International, Ohé en Laak, The Netherlands; **Sudi Sudarshan**, principal consultant, Global Mobility Strategies, USA; **Stephan Paischer**, head of product management and market intelligence, Semperit AG Holding, Vienna, Austria; and everyone else who had a go.

SOLUTIONS

**David Mann**

(Neat solution shown in image below)

**Michele Girardi**

*The answer could be 8200, see explanation below*

*7429 can be factorized as 17*19*23 ;*

*17 and 23 are present in the table, 19 is the average of 12 and 26 ,*

*putting the numbers in order as per the table, 7429 = (12+26)/2*23*17 .*

*Applying the same rule, the missing value is 8200 = (26+15)/2*16*25*

**Andrew Knox**

*Answer: 8200 (which I don’t like, but is based on an observation which clearly must hold a strong clue to the answer)*

*Having lost interest on this puzzle in several attempts, I approached this from a different viewpoint: how could you arrive at the number 7429?*

*Factorising gives 7429 divisible by 17, 19 & 23 (all prime numbers) (so 7429 = 17 x 19 x 23).*

*17 & 23 are both contained in the second column of the first table. How then could one arrive at the number 19? Adding the first column numbers 12 & 26 we get 38, so dividing by 2 that is an average of 19. Applying the same manipulation to the second table gives 20.5 x 16 x 25 = 8200. *

*If 7429 were not such a special number I imagine it would have been much more difficult to look at averaging the numbers in the first column to give the first of the three number needed. Of course, this may not be the correct answer!*

**Sudi Sudarshan**

*Solution 1 *

*((12+26)*23*17)/2 = 19*23*17 = 7429*

*((26+15)*16*25)/2 = 41*16*25/2 = 8200*

*Solution 2 *

*7429 is derived as 74 is derived by flipping the digits of the second number and adding to the first number i.e., 62+12 = 74; 29 is derived by reducing the digits of either the first or the second number by 1 and adding to the other number, i.e., 12+17 = 29 or 23+06 = 29. 51+26 = 77; 05+25=30 and so the answer is 7730*

**Stephan Paischer**

*The answer is 8200. I add the figures of the first column and divide by 2, and then multiply with the figures of the second column.*

*(12 + 26) / 2 * 23 * 17 = 7429*

*(26 + 15) / 2 * 16 * 25 = 8200*

*David Mann*

Question 1: **My type of town**

Quebec, Warsaw, Edinburgh, Rome, Tokyo, ?,

**Answer**: Well done to everyone who recognised this as a QWERTY, QUERTZ or other keyboard sequence (see selected Solutions below) – especially the first five on our list who hit town well before any clues were issued: **Antonella Pagliarulo**, product development manager, Performance Polymer Solutions, Thomas Swan & Co. Ltd, Consett, County Durham, UK; **Stephan Paischer**, head of product management and market intelligence, Semperit AG Holding, Vienna, Austria; **Michele Girardi**, quality manager, Scame Mastaf SpA, Suisio, Italy; **Andrew Knox**, Rubbond International, Ohé en Laak, The Netherlands; **John Coleman**, membership manager, Circol ELT, Dublin, Ireland; **Amparo Botella**, responsable de Compras y Calidad, Ismael Quesada SA, Elche, Alicante, Spain; **David Mann**, Polymer Business Development (retired), UK; **John Bowen**, rubber & tire industry consultant, Bromsgrove, UK; **Paul Michael Abosch**, head, sales & marketing, Americas – Specialty Blacks, PCBL Ltd, Anise Dr Sarasota, Florida, USA; **Jose Padron**, laboratory analyst, Toyoda Gosei, Waterville, QC, Canada; and everyone else who had a go.

SOLUTIONS

**Antonella Pagliarulo**

*Considering the hint in the title “my TYPE of town”, as from typing on a keyboard, and looking at the initials of the towns, the last town should start with a Y, to compose the word QWERTY, which is a keyboard layout. Since the other towns are capitals, either of a province or of a country, the last one could be Yerevan, capital of Armenia.*

**Stephan Paischer**

*Looking at my keyboard, the answer could be Zurich or Zagreb.The mentioned cities follow the upper letters on the keyboard from left to right, the next in line being Z. At least it works for a German type keyboard…. For a British keyboard layout it would be U – so the answer could be Ulaanbaatar or Utrecht.*

**Michele Girardi**

*The next one could be Yaoundé or Yamoussoukro:*

*- the cities listed are capitals *

*- their initials are QWERT , like the letters of the QWERTY keyboard*

*The next one should be a capital starting with Y*

**John Coleman**

*All these city names begin follow the QWERTY keyboard system, so the next city should begin with Y, e.g. York, Yerevan or Yokohama… And given tyres reliance on rubber, let’s settle on Yokohama as the answer!*

**Andrew Knox**

*Answer: This looks like a trip around a keyboard that starts with QWERTY, so the answer is a (capital) city starting with the letter "Y", so Yamoussoukru, Yaoundé, Yaren and Yerevan would all fit. As Quebec is not a country capital, Quito might have been a better choice here? If the list is just cities around the world, then York would fit too.*

**Amparo Botella**

*The last word joining the initials of each city is: QWERT so the Y is missing. To find a city starting with Y and that have something in common with Quebec, Warsaw, Edinburg, Rome and Tokyo we find Yerevan, all these cities are/were fortified cities.*

**David Mann**

*Yamoussoukro – they’re capital cities that start with the letters across an English keyboard. French readers might have had to start with Athens and Zagreb!*

**John Bowen**

*Next could be Yannoon [China] or York [England]*

*A contender could be Kampala, capital of Uganda.*

*The rest all seem to be state capitals of some sort, all of which are built on a number of hills; Kampala has seven.*

**Jose Padron**