Today Puzzle #781
Puzzle No. 781鈥� Monday 13 July
Professor Dodo’s landline number consists of 6 digits. If he forgets it he can easily reconstruct it as it is divisible without remainder by every number from 1 to 16 inclusive. What is his number?
Today’s #PuzzleForToday has been set by Chris Maslanka writer and broadcaster, specialising in puzzles and problem solving
Click here for the answer
Dodo's phone number has to be divisible by 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 & 6. Break down each of these factors into products of prime numbers: 2, 3, 2 X 2, 5, 2 X 3, 7, 2 X 2 X 2, 3 X 3, 2 X 5, 11, 2 X 2 X 3, 13, 2 X 7, 3 X 5 and 2 X 2 X 2 X 2.
The smallest set we can construct so that each entry in that list of numbers may be found is (2 X 2 X 2 X 2) X (3 X 3) X 5 X 7 X 11 X 13 = 720720; so that is the smallest number divisible by all the numbers from 1-16 and hence Dodo's number.
-
![]()
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...
