Clock Around

Given a time in one city, work out the matching local time in each other city's timezone and type it in. Then solve the twist: find the one hour that falls within daytime for every city at once.

• Enter each city's local time in HH:MM based on its zone offset
• Account for which cities are ahead of or behind the reference
• Pinpoint the hour that's daytime across all of them
• A hint is available, and difficulty adds more cities and zones

• Easy or Medium difficulty for fewer or more cities
• Daily puzzle or Practice for unlimited rounds

• Desktop: type times into the HH:MM fields and click Submit
• Phone & tablet: tap fields (numeric keypad) and tap Submit

• Convert everything relative to the given city, add hours going east, subtract going west
• Watch for day rollovers past midnight when a city is far ahead or behind
• For the daytime hour, look for the overlap window the eastern and western cities share

Clock Around is a timezone-conversion puzzle that tests how zones and offsets line up around the globe.

• Skills: time zones, UTC offsets, longitude and time
• Best for: roughly grades 5–10 (ages 10–16)
• For parents & teachers: time zones made logical, not just looked up.

Converting a time between cities is arithmetic over time zones, and finding the one hour that is daytime in all of them is the scheduling problem that follows.

Pairing the two is the original structure.

The second question is the one that actually arises, and it is often unanswerable — a spread of more than about sixteen hours has no common waking hour at all. Time zones are also political rather than geometric, so the offsets include half-hours, quarter-hours and one country spanning five zones on a single clock.

Clock Around is a timezone-conversion puzzle that tests how zones and offsets line up around the globe. It's an original, free browser game built in-house for PlayPendium.

A free, original browser game on PlayPendium. No download, no install.