10 riddles

Numbers

These number riddles turn on patterns, sums and sequences. Some ask for a mystery number from a few clues, others for the next term in a sequence, a weight on a set of scales or the fewest tokens to pay a total. Plain arithmetic is enough. Each riddle has a hint, the answer and a short explanation, from Easy up to Genius.

Mirror Clock: 13:31 Video
Hard Numbers

Mirror Clock: 13:31

How Many Routes: One Cone Video
Hard Numbers

How Many Routes: One Cone

Longest Roman Year Video
Hard Numbers

Longest Roman Year

Two Candles: 20 cm and 15 cm Video
Hard Numbers

Two Candles: 20 cm and 15 cm

Hands Apart: 3:30 Video
Hard Numbers

Hands Apart: 3:30

Fewest Tokens: Pay 11 Video
Hard Numbers

Fewest Tokens: Pay 11

Fewest Tokens: Pay 18 Video
Hard Numbers

Fewest Tokens: Pay 18

Lamp Code: Show 22 Video
Hard Numbers

Lamp Code: Show 22

Fewest Tokens: Pay 14 Video
Hard Numbers

Fewest Tokens: Pay 14

Three Turning Rings Video
Hard Numbers

Three Turning Rings