What pressure is exerted by the tip of a nail struck with a force of 20000 N Assume the tip is a 1.5-mm-radius circle?

The idea is to divide force / area. Ask a separate question if you need help to find the area of the circle. And be sure to convert the area of the circle to square meters (1 meter = 1000 mm, therefore, 1 square meter = 1 million square millimeters). Note: Don't get too surprised if the answer is a large number.