Place four pebbles on the sand in the form of a square. Keep adding as few pebbles as necessary to double the area. How many extra pebbles are added each time?
Through the Window
Age 7 to 11 Challenge Level
The store in my town which sells windows calculates the price of windows according to the area of glass used and the length of frame needed.
Can you work out how they arrived at the prices of the windows below?