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Square Pegs

Which is a better fit, a square peg in a round hole or a round peg in a square hole?

Bull's Eye

What fractions of the largest circle are the two shaded regions?

Blue and White

Identical squares of side one unit contain some circles shaded blue. In which of the four examples is the shaded area greatest?

Squaring the Circle

Age 11 to 14 Challenge Level:

Plenty to keep you busy here.

You can see a full quarter of the circle and you can extrapolate from this fairly accurately.