The answer, surprisingly, is MORE than 2000 circles.
Students work in groups to investigate properties of staircase numbers.
The questions range from easy to very challenging. A4 paper is 297 mm by 210 mm. A4 paper is part of a series of paper sizes from A0 to A9. A sheet of A5 is the same shape as a sheet of A4, but half the area. It is also worthwhile finding the area of a sheet of A0 paper.