Plant 9 flowering cherry trees in 10 straight rows with 3 trees per row. (This is not a misprint.)
Set 01
Moving Circles
If you figure out which one of these 6 circles to move, and where, you will wind up with 4 straight rows of 3 circles per row.
Manhole Covers
There is a very practical and important reason why manhole covers are round. No polygonal shape will do. Can you figure out what the reason is? (The answer is not “because manholes are round.”)
Overlapping Squares
These overlapping squares each have sides of 10 cm. One corner of one square is at the center of the other square. What is the area of the shaded region?
Queens on a Chessboard
Put eight x‘s into this 8-by-8 grid so that no two x‘s are in line with each other vertically, horizontally, or diagonally.
Chess players note: You are being asked to place eight queens on a chessboard so that no queen can capture any other queen.