Chapter 3

Mike: That took a while to compute. How about something a little shorter?

The image consists of a white background containing a grid of square boxes, each box is outlined in black and contains two numbers in black. The grid consists of three rows, each containing four boxes. The numbers inside the boxes are positioned at the top left and bottom centre. Working from top left to bottom right in the grid the numbers in the boxes are: 74(top) 183.84 (bottom); 1 (top) 1.008 (bottom); 85 (top) [210] bottom; 53 (top) 126.90 (bottom); 16 (top) 32.06 (bottom); 28 (top) 58.693 (bottom); 10 (top) 20.180 (bottom); 15 (top) 30.974 (bottom); 71 (top) 174.97 (bottom); 16 (top) 32.06 (bottom); 8 (top) 15.99 (bottom); 10 (top) 20.180 (bottom)

The image above contains a hidden question. Please enter the answer to the question in the box below. If the answer is a number please enter it using numerals rather than words.

To deter guessing without thinking, we ask that you also solve the following simple arithmetic problem before checking your answer:

What is 5 × 2 + 5?

This problem was first solved on Mon 26th January at 4:01:53pm

Alan Turing Cryptography Competition 2026 is organised by the The Department of Mathematics at The University of Manchester.
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