# Somebody hacked my clock

Harvey the hacker hacked my clock. At first, the results made no sense, but I eventually figured out his logic.

At 12:00, the clock shows 12:19
At 12:01, the clock shows 12:15
At 12:02, the clock shows 12:18
At 12:03, the clock shows 12:18
At 12:04, the clock shows 12:17
At 12:05, the clock shows 12:18
At 12:06, the clock shows 12:19
At 12:07, the clock shows 12:16
At 12:08, the clock shows 12:20

At 12:09, what will the clock show, and why?

At 12:09 the clock should display

12:19, as the minutes count the 19 lit segments of 12:09 in seven-segment display.

The start 12:0 has 13 segments, then 0>6, 1>2, 2>5, 3>5, 4>4, 5>5, 6>6, 7>3, 8>7, 9>6.

• The image shows a differently counting (hexadecimal) device though. – Bass Jul 20 '19 at 20:51

If your unhacked clock displayed 9 like this

then at 12:09 your hacked clock will show 12:18.

If your unhacked clock displayed 9 like this

then at 12:09 your hacked clock will show 12:19.

The minutes have been hacked to display the count of lit segments in the unhacked time.

This should be a comment on Tom's answer but I can't put spoiler tags or images in a comment.