## Hard

### Puzzling update: January 2022

It has come to our attention that the hard puzzle published in this issue has more than one solution. Professor Mestel has kindly provided update to this puzzle for us:

• In a game of chess White played his King to e5, which was met by 5... Qa5 checkmate. What was the game?

The original puzzle printed in issue 51 is:

• The routine in a game of chess, White’s first move was 1e4 and Black’s fifth move was 5... Qa5 checkmate. What was the game?

Happy puzzling!

The solution to this puzzle is:

1 e4 Nc6; 2 Ke2 Nd4+ 3 Ke3 c6 4 Kf4 Ne2+ 5 Ke5 Qa5 mate

This solution applies to the original puzzle printed in the magazine and the update published online in January 2022.

## Very hard

What is the smallest number of times you have to hit the ball over the net in order to win a set of tennis at Wimbledon?

Solution:

One. The ordinary games consist of a sequence of double faults leaving the scored tied at 6-6. In the tie-break, I start with a double-fault and the double-faulting continues until I am 6-5 ahead. Finally, I serve an ace and win the tie-break 7-5. I don’t think the spectators would enjoy this match.

## Fiendish

What is the smallest number of tricks one side must win in order to win a rubber of bridge without ever holding an ace or a trump? No revokes take place.

All puzzles set by Professor Jonathan Mestel, Professor of Applied Mathematics, Department of Mathematics.

Solution:

Two. In the first game the opponents score five clubs with two overtricks, netting 140 points. Emboldened by this, they next try a grand slam which is doubled and redoubled failing by two vulnerable tricks for -1000. They then score a second game for +140 and earn the double game bonus of +700, but are still -20 overall.

## How to enter:

The first 10 readers to send the 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 52 in May 2022, and solutions published on this page.

Entries close on 31 January 2022.

Congratulations to everyone who found the correct solutions and well done to our winning puzzlers:

• Stephen Barnett (PhD Physics 1985)
• David Hyde (MSc Engineering Hydrology 1985)
• Damian Chu (Computing 1985, PhD 1993)
• Chris Glover (Chemical Engineering 1974)
• Martin Marriott (MSc Civil and Environmental Engineering 1981)
• Sean McHale (MBBS Charing Cross and Westminster Medical School 1986)
• Todd Davies (Mathematics 2019)
• Paul Holt (Physics 1983)
• David Lloyd Owen (Physics 1972)
• Adrian Tottenham (MSc Chemical Engineering 1981)