Rules
You have to divide the grid into rectangular and square pieces such that each piece contains exactly one number, and that number represents the area of the rectangle.
Are you lost? Check out the step by step tutorial

Tap/click and drag to draw a rectangle.

Zooming
Pinch with two fingers to zoom in/out. If you use a mouse you can use the scroll button.

Moving
Pinch with two fingers and drag to move the puzzle. If you use a mouse you can click and drag with the middle (scroll) button.