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Sunday Times Teaser 3177 – Prime Birthday Card

by BRG on August 11, 2023

by Bill Kinally

Published Sunday August 13 2023 (link)

On her 11th birthday, Ann’s older brother Ben gave her a card on which he had drawn a 5×5 square grid with a different prime number in each of the cells. Every 5-cell row, column and diagonal had the same sum and, noting that 1 is not a prime, he used primes that made this sum as small as possible. The centre cell contained Ann’s age. All but one of the primes containing a digit 7 were on the two diagonals, the largest of these being in the bottom right corner. Two cells in the far right column contained a digit 5 as did two cells of the 4th row down. Four of the cells in the middle row contained a digit 3, and the largest prime on the grid was in the same column as two single digit primes.

What are the five prime numbers on the top row of the card?

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3 Comments Leave one →
  1. BRG permalink

  2. John Z permalink

    Your first line which I assume is:

    is missing.

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