Based on the following info graciously provided by an architect for designing circular/nonlinear stairs we can see that the typical spiral staircase has a thread depth of 12" and a height, or rise, of about 7-3/4". The note paper would have been 11-1/2" tall by 8-1/2". 3 sheets side by side would equal approx. 26" which is well within the recommended width for a tread of 30". Two steps equal the height of the jump to go from the second tread to the floor, which is 15-1/2" in the vertical and 12" in the horizontal to clear the first tread. Doesn't sound like a big accomplishment to me.

"Let's do the Circular (really, nonlinear) Stair Rules (drawn liberally from experience and the International Residential Code).

Tread Rule. Not narrower than 3'. Always of equal dimension in 2d plan view and elevations.

Unit Rise Rule. 7 3/8" - 7 3/4", vertically.

Walkline Rule. 1'-0" outside the inner arc in two dimension plan view, i.e., on the horizontal, that line at which unit run equals 10".

Tread (without nosing) depth, or Unit Run Rule (really a corollary to the Walkline Rule). Horizontally — 10" at the walkline of nonlinear stairs; 12" for straight stairs associated with nonlinear stairs.

Local codes may vary. Check it out. Local codes may not even address these rules. Feel free to use these rules entirely at your own risk. The AG does."

http://www.beforethearchitect.com/DC-STRs.htm

It may be helpful to point out that the 12" tread depth is the maximum depth at the outer circumferance of the stair. The tread narrows continuously to a depth of 10" at a point 12" from the center of the stair. This means that, of the three pages left side by side, the left most page would extend beyond the tread about 3/4" to the front and back, less the amount of the page torn off and left on the pad. The middle page would pretty much match the tread depth at 11" and the right most page would fit just within the 12" tread.
At the point where someone would typically step, approximately the center of the tread width, the depth would be about 11", not 12".

Thus, If you can jump outward about 11" and down about 16" you could have cleared over the last step and the Ransom Note.