Below you find a quadrilateral within a [color=#1551b5]blue square of side length 10[/color]. In the upper right corner a [color=#1551b5]blue unit square[/color] is displayed. The task is to estimate the size of the grey quadrilateral for the given units.[br]You may show the grid for a hint. [br]Enter your estimation in the input field and press enter to get feedback.[br]Press the button (New Problem) to generate a new quadrilateral.