Solstice Puzzles 

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It's summer solstice — and therefore puzzle — time again! Here are some of the best puzzles to have come my way in the last 12 months for your entertainment and frustration. So, deep breath and ...

Laterally Yours

When this old chestnut was posted in Britain's New Scientist, everyone got the obvious "aha" answer, but readers found at least 10 more imaginative solutions. Notice the left column adds up to 21, while the right column adds up to 24. By moving just one card, make the left and right columns add up to the same total.

Six Weeks of Seconds

Which is larger, the number of seconds in six weeks or 10! (1x2x3x4x5x6x7x8x9x10)?

Squares

Four squares. The total area of the two red squares is 20 units. What's the total area of the yellow squares?

Instant Arithmetic

Quick (no calculator!), what's (5,000²) – (4,999²)?

The Prize

This little logic puzzle keeps popping up in my inbox. The set-up is that logicians Alice and Bob are shown five cards, with one card hiding a prize. Alice is told the shape of the prize card, while Bob is told the color of the prize card. Alice knows Bob knows the color, and Bob knows Alice knows the shape.

Host: (Round 1) "Do either of you know where the prize is?" (Silence)

Host: (Round 2) "Do you know now?" (Silence)

Host: (Round 3) "Do you know now?"

Alice and Bob: "Yes!"

Where's the prize?

Joining

Join A to A, B to B and C to C with lines that don't cross or go outside the frame.

Answers coming soon ...

Barry Evans (he/him, barryevans9@ yahoo.com) welcomes any puzzle ideas for future use in Field Notes.