# 1.1. Condition:

On the International Space Station, there were electronic clocks displaying time in the format HH : MM. Due to an electromagnetic storm, the device started malfunctioning, and each digit on the display either increased by 1 or decreased by 1. What was the actual time when the storm occurred, if immediately after it the clocks showed 20:09?
Answer: 11:18

Solution.

The first digit before the breakdown could have been 1 or 3, but since the electronic device does not display values above 24 hours, only 1 meets the condition. The second and third digits in sequence are zeros, so before the breakdown, they could only have been 1. The last digit is 9, which means before the breakdown, it could only have been 8. Hence, we get the answer: $11: 18$.