The ornamental design for a calculatorflapbookcover, as shown and described.
FIG. 1 is a top plan view of the inside of a calculator flap book cover
showing my new design;
FIG. 2 is a bottom plan view thereof; and,
FIG. 3 is a top plan view thereof, with the flap in a closed position.
The broken lines in FIG. 3 are for illustrative purposes only and form no
part of the claimed design. The claim as disclosed is understood to be of
conventional thickness.