A light-nanosecond is the distance that a photon can travel at the speed of light in one billionth of a second. The speed of light is 3 × 10⁸ ms⁻¹. How far is a light-nanosecond?
Select one option, then click Submit.
3 cm
30 cm
3 m
30 m
300 m
Select an option, then submit.
Sign in or create an account to reveal answers, view the solution, and save your progress. Create a free account to unlock practice and keep track of your work.
Senior Mathematical Challenge (2022)
One puzzle per day. Cryptarithm, Magic Square, Summit. No sign-up required to play.
Play daily puzzle →Interactive problems and curated lessons—water pouring, magic squares, knight's tour, and more.
Browse library →See how you rank. Top solvers by problems solved correctly. Sign in to climb the ranks.
View leaderboard →Senior Mathematical Challenge (2022)