Today Puzzle #675
Puzzle No. 675鈥� Thursday 13 February 2020
To celebrate his birthday, Bobby is asking you to work out his current favourite number. Like Johnny Ball's 1970s TV show, Bobby is thinking of a number. His two-digit number is a prime number. When the digits are reversed, it is still a two-digit prime number. The sum of both two-digit numbers adds up to the number of modern constellations in the sky. Assuming he picks the smaller of the two possible two-digit numbers, what is Bobby's current favourite number?
Today’s #PuzzleForToday has been set by Bobby Seagull, school maths teacher, author and Cambridge University Doctorate student.
Click here for the answer
17.
17 and 71 are the two prime numbers. Added together, they make 88 which is the number of constellations in the sky.
-
![]()
Puzzle for Today 鈥� Index
Find all of the currently available Puzzles for Today, with answers.
More fiendish brain-teasers and quizzes on 大象传媒 Radio...
-
![]()
From autumn leaves to the magic roundabout: test yourself with our favourite quizzes.
-
![]()
We asked the intelligence agency to set our listeners a code-cracking challenge... Can you solve it?
-
![]()
Quiz: How many of these Mastermind music questions can you answer?
Here's a chance to find out whether your specialist subject on Mastermind could be the entire history of music.
-
![]()
Six conundrums to grapple with, including the Riddle of the Sphinx. Try not to forfeit your life...
