Ready to test your little grey cells? Imperial’s best minds set the ultimate puzzle challenge.

Hard

If you follow my rule with 15, then you’ll surely get 74. The routine can then also be seen, with what number you wish – say a score! With a score you can get 71, but with five just 80 you’ll see. So perhaps you can figure for fun, what the answer with 30 will be.

Set by JAH Hunter in Fun with Figures, submitted by Robb Gosine, postgraduate student

See the answer

See the answer

Answers will be added after the closing date

Very hard

You are standing at the centre of a circular field of radius R. The field has a low wire fence around it. Attached to the wire fence (and restricted to running around the perimeter) is a large, sharp-fanged, hungry dog. You can run at speed v, while the dog can run four times as fast.

What is your running strategy to escape the field?

Set by puzzles.nigelcoldwell.co.uk, submitted by Naran Gorsia

See the answer

See the answer

Answers will be added after the closing date

Fiendish

A scientist calls an old school friend – who is an artist – to arrange a drink that evening.

The scientist, who prides himself on his accuracy, sets the time for them to meet. Both of them arrive at the correct time but the artist arrives 30 minutes earlier than his friend.

How is that possible?

Set by Pete Champ (BSc Electrical Engineering 1984)

See the answer

See the answer

Answers will be added after the closing date

How to enter:

Senders of correct solutions for two or more of the puzzles will be entered into a prize draw to win a book e-voucher for the value of £10.

Winners' names will be in Imperial 51 in November 2021, and solutions published on this page.

To enter, please email imperialmagazine@imperial.ac.uk.

Entries close on 31 July 2021.