As the clocks go forward this spring, see if you can solve these puzzles based on ancient calendars.

When the clocks change for Daylight Saving Time, it can often involve a bit more mental arithmetic than usual as we try to figure out our schedules. This is especially true for those of us trying to navigate different time zones.

For most of the US, the clocks go forward one hour on the second Sunday in March – unless you're in Arizona and Hawaii, which do not observe Daylight Saving Time. Spare a thought for the Navajo Nation living in Arizona – they move to daylight savings time even though the rest of the state stays on standard time.

And for those making transatlantic calls, the time difference is a little shorter for the next three weeks as the UK and the rest of Europe do not move to their summer time schedule until later in March. But even here there can be mental agility needed - the clocks at the Royal Observatory in Greenwich, London, are a frequent cause of confusion for visitors as they remain on GMT throughout the summer.

In the ancient world, there were far more radical changes to the way people observed and formalised time. The changes to the calendars used by the Romans, for instance, led to seemingly impossible conundrums.

To help limber up your brain for the weeks ahead, we've put together the following time-based riddles with the advice of Helen Parish, professor of history at the University of Reading in the UK. Scroll to the bottom of the article for the answers – or if you'd like a clue,

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