Solve our 25th anniversary puzzle and win tickets to the celebratory event

15 June 2017

Can you solve our 25th anniversary puzzle?

This year, the Isaac Newton Institute marks its 25th anniversary. To celebrate, we will be hosting a grand day of talks and celebrations. Taking place on Thursday 20 July 2017, the prestigious list of attendees includes many notable mathematicians and affiliates of the Institute. But perhaps most exciting of all is the following: a conversation between Sir Andrew Wiles and his biographer Simon Singh on how Andrew found the proof for one of the hardest problems in mathematics.

To those unfamiliar with the story, that problem was Fermat’s Last Theorem and Professor Wiles’ elegant solution – which was presented at INI in 1993 – ended 358 years of frustration amongst some of the greatest minds ever to pursue mathematics as a science.

And now the part where you come in: INI is offering the chance for one lucky winner (plus a guest) to attend this historic event. The only catch is that you must be able to solve the following problem:

The Isaac Newton Institute’s 25th anniversary puzzle

Can you make all of the numbers from 1 up to 100 using, for each sum, all four of the digits in 1992? You must use each digit precisely once but you can use them in any order. You may also use a combination of any of the following operators: addition, subtraction, multiplication, division, parentheses and concatenation (e.g. “29”), square root, factorial (!) and exponentiation.

E.g.      1 = 9 – 9 + 2 – 1

100 =   99 + 2 – 1

The winner, selected from those with the most correct answers, will be invited (plus one guest) to attend this momentous occasion*.


1) Concatenation. You may concatenate only the original given digits.  Thus you cannot make 87 from the concatenation of (9 – 1) and (8-1).

2) Decimal points and recurring decimals.  The rules of this puzzle are based on the rules of “Four Fours” and hence you can use a decimal point and a recurring decimal.  But in fact you don’t need to!

3) Square roots.  You don’t need to use the 2 to indicate a square root but any other root would have to be acheived using a fractional power.

Answers should be sent to by Friday 7 July 2017.

*(please note that we cannot cover travel costs or accommodation)

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