Changes at Chequers
I started with a six-by-six grid with a 0 or 1 in each of its 36 squares: they were placed in chequerboard style with odd rows 101010 and even rows 010101. Then I swapped over two of the digits that were vertically adjacent. Then in three places I swapped a pair of horizontally adjacent digits.
In the resulting grid I read each of the six rows as a binary number (sometimes with leading zeros) and I found that three of them were primes and the other three were the product of two different primes. The six numbers were all different and were in decreasing order from the top row to the bottom.
What (in decimal form) were the six decreasing numbers?
Send your solution to: The Sunday Times Teaser 3212, PO Box 29, Colchester, Essex CO2 8GZ or email puzzle.entries@sunday-times.co.uk. The first two correct solutions opened after next Saturday each win a £20 Waterstones voucher. Open to 18+ UK & ROI residents only.
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Solution to Teaser 3210
45%
The winners are: D Jukes, Nailsea, Somerset; B Smith, Brighton, East Sussex.