skip to main content

Brain Teasers and Puzzles

Please consider supporting BrainBashers [hide]

Puzzle Details

At midnight at the start of Monday, January 1st, Professor Stone set two old-fashioned clocks to the correct time.

One clock gains one minute every hour and the other loses two minutes every hour.

1. When will the clocks next show the same time as each other?
2. When will the clocks both show the correct time?

Puzzle Copyright © Kevin Stone

workings hint hide answer

1. Midnight after 10 days, which is 240 hours later. They both show 4 o'clock, one clock has gained 240 minutes (4 hours) and the other has lost 480 minutes (8 hours).

2. Midnight after 30 days, which is 720 hours later. They both now show 12 o'clock.

Share link:


Note: BrainBashers has a Dark Mode setting.