I own a digital 24-hour clock (i.e., a military time clock) that displays in HH:MM format. Each digit uses the standard seven-segment display in which seven lights toggle on or off to form numbers, as ...

One string in each of the following pairs can be unraveled into a circle—the so-­called unknot. Which one is it? Show puzzle solution The knots at the top left and the bottom right can be unraveled ...

While each product featured is independently selected by our editors, we may include paid promotion. If you buy something through our links, we may earn commission. Read more about our Product Review ...